MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()

16 files changed, 1536 insertions, 16 deletions

diff --git a/mysql-test/include/type_hrtime.inc b/mysql-test/include/type_hrtime.inc
index d666dc63bba..128e3295133 100644
--- a/mysql-test/include/type_hrtime.inc
+++ b/mysql-test/include/type_hrtime.inc
@@ -18,7 +18,7 @@ insert t1 values (20101211030405.789e0);
 insert ignore t1 values (99991231235959e1);
 select * from t1;
 --replace_regex /121000/121094/ /457000/457031/ /789000/789062/
-select truncate(a, 6) from t1; # Field::val_real()
+select cast(a AS double(30,6)) from t1; # Field::val_real()
 select a DIV 1 from t1; # Field::val_int()
 select group_concat(distinct a) from t1; # Field::cmp()
 alter table t1 engine=innodb;
diff --git a/mysql-test/main/func_time.result b/mysql-test/main/func_time.result
index 0b5fb46c1d5..a9d4f365f9b 100644
--- a/mysql-test/main/func_time.result
+++ b/mysql-test/main/func_time.result
@@ -2180,13 +2180,13 @@ CREATE TABLE t1 (a TIMESTAMP(3));
 INSERT INTO t1 VALUES ('2001-01-01 10:20:30.999');
 SELECT CAST(COALESCE(a,a) AS SIGNED) AS c1, CAST(COALESCE(a,a) AS DECIMAL(25,3)) AS c2, ROUND(COALESCE(a,a)) AS c2  FROM t1;
 c1	c2	c2
-20010101102030	20010101102030.999	20010101102031
+20010101102030	20010101102030.999	2001-01-01 10:20:31
 DROP TABLE t1;
 CREATE TABLE t1 (a TIME(3));
 INSERT INTO t1 VALUES ('10:20:30.999');
 SELECT CAST(COALESCE(a,a) AS SIGNED) AS c1, CAST(COALESCE(a,a) AS DECIMAL(25,3)) AS c2, ROUND(COALESCE(a,a)) AS c2  FROM t1;
 c1	c2	c2
-102030	102030.999	102031
+102030	102030.999	10:20:31
 DROP TABLE t1;
 SELECT
 CAST(COALESCE(DATE('2001-01-01'),TIMESTAMP('2001-01-02 10:20:30')) AS SIGNED) AS c1,
diff --git a/mysql-test/main/timezone2.result b/mysql-test/main/timezone2.result
index 7b5b2e6dd71..b858e761a81 100644
--- a/mysql-test/main/timezone2.result
+++ b/mysql-test/main/timezone2.result
@@ -610,5 +610,31 @@ DROP TABLE t1;
 SET timestamp=DEFAULT;
 SET time_zone=DEFAULT;
 #
+# MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+#
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (i INT, d TIMESTAMP(6));
+SET timestamp=1288479599.999999  /* this is the last second in summer time */ ;
+INSERT INTO t1 VALUES (1,NULL);
+SET timestamp=1288479600.000000 /* this is the first second in winter time */ ;
+INSERT INTO t1 VALUES (2,NULL);
+SELECT i, d, UNIX_TIMESTAMP(d) FROM t1 ORDER BY d;
+i	d	UNIX_TIMESTAMP(d)
+1	2010-10-31 02:59:59.999999	1288479599.999999
+2	2010-10-31 02:00:00.000000	1288479600.000000
+CREATE TABLE t2 (i INT, d TIMESTAMP, expected_unix_timestamp INT UNSIGNED);
+INSERT INTO t2 SELECT i, ROUND(d) AS d, ROUND(UNIX_TIMESTAMP(d)) FROM t1;
+# UNIX_TIMESTAMP(d) and expected_unix_timestamp should return the same value.
+# Currently they do not, because ROUND(timestamp) is performed as DATETIME.
+# We should fix this eventually.
+SELECT i, d, UNIX_TIMESTAMP(d), expected_unix_timestamp FROM t2 ORDER BY i;
+i	d	UNIX_TIMESTAMP(d)	expected_unix_timestamp
+1	2010-10-31 03:00:00	1288483200	1288479600
+2	2010-10-31 02:00:00	1288476000	1288479600
+DROP TABLE t2;
+DROP TABLE t1;
+SET timestamp=DEFAULT;
+SET time_zone=DEFAULT;
+#
 # End of 10.4 tests
 #
diff --git a/mysql-test/main/timezone2.test b/mysql-test/main/timezone2.test
index d0c6588cd05..9d364224311 100644
--- a/mysql-test/main/timezone2.test
+++ b/mysql-test/main/timezone2.test
@@ -551,6 +551,32 @@ DROP TABLE t1;
 SET timestamp=DEFAULT;
 SET time_zone=DEFAULT;
 
+--echo #
+--echo # MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+--echo #
+
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (i INT, d TIMESTAMP(6));
+SET timestamp=1288479599.999999  /* this is the last second in summer time */ ;
+INSERT INTO t1 VALUES (1,NULL);
+SET timestamp=1288479600.000000 /* this is the first second in winter time */ ;
+INSERT INTO t1 VALUES (2,NULL);
+SELECT i, d, UNIX_TIMESTAMP(d) FROM t1 ORDER BY d;
+
+CREATE TABLE t2 (i INT, d TIMESTAMP, expected_unix_timestamp INT UNSIGNED);
+INSERT INTO t2 SELECT i, ROUND(d) AS d, ROUND(UNIX_TIMESTAMP(d)) FROM t1;
+
+--echo # UNIX_TIMESTAMP(d) and expected_unix_timestamp should return the same value.
+--echo # Currently they do not, because ROUND(timestamp) is performed as DATETIME.
+--echo # We should fix this eventually.
+
+SELECT i, d, UNIX_TIMESTAMP(d), expected_unix_timestamp FROM t2 ORDER BY i;
+DROP TABLE t2;
+
+DROP TABLE t1;
+SET timestamp=DEFAULT;
+SET time_zone=DEFAULT;
+
 
 --echo #
 --echo # End of 10.4 tests
diff --git a/mysql-test/main/type_datetime_hires.result b/mysql-test/main/type_datetime_hires.result
index 38e2c2a5ac8..ebb9c6032b9 100644
--- a/mysql-test/main/type_datetime_hires.result
+++ b/mysql-test/main/type_datetime_hires.result
@@ -17,8 +17,8 @@ a
 2010-12-11 01:02:03.456
 2010-12-11 03:04:05.789
 2010-12-11 15:47:11.123
-select truncate(a, 6) from t1;
-truncate(a, 6)
+select cast(a AS double(30,6)) from t1;
+cast(a AS double(30,6))
 0.000000
 20101211002003.120000
 20101211010203.457031
@@ -352,3 +352,542 @@ NULL
 978307200.0000
 DROP TABLE t1;
 SET @@time_zone=DEFAULT;
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+#
+CREATE TABLE t1 (a1 DATETIME(6), a2 DATETIME(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+ROUND(a1) AS r1,
+ROUND(a2) AS r2,
+TRUNCATE(a1,0) AS t1,
+TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `r1` datetime DEFAULT NULL,
+  `r2` datetime DEFAULT NULL,
+  `t1` datetime DEFAULT NULL,
+  `t2` datetime NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t2;
+DROP TABLE t1;
+CREATE TABLE t1 (a DATETIME(6));
+INSERT INTO t1 VALUES
+('0000-00-00 00:00:00.999999'),
+('0000-00-00 23:59:59.999999'),
+('0000-00-01 00:00:00.999999'),
+('0000-00-01 23:59:59.999999'),
+('0000-00-31 23:59:59.999999'),
+('0000-01-01 00:00:00.999999'),
+('0000-01-01 23:59:59.999999'),
+('0000-01-31 23:59:59.999999'),
+('0000-02-28 23:59:59.999999'),
+('0000-12-31 23:59:59.999999'),
+('0001-01-01 00:00:00.999999'),
+('0001-02-28 23:59:59.999999'),
+('0001-12-31 23:59:59.999999'),
+('0004-02-28 23:59:59.999999'),
+('0004-02-29 23:59:59.999999'),
+('2000-02-29 23:59:59.999999'),
+('2000-12-31 23:59:59.999999'),
+('9999-12-31 23:59:59.999999');
+SELECT a, TRUNCATE(a,0) FROM t1;
+a	TRUNCATE(a,0)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59
+0000-00-31 23:59:59.999999	0000-00-31 23:59:59
+0000-01-01 00:00:00.999999	0000-01-01 00:00:00
+0000-01-01 23:59:59.999999	0000-01-01 23:59:59
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+SELECT a, TRUNCATE(a,1) FROM t1;
+a	TRUNCATE(a,1)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.9
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.9
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.9
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59.9
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+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.9
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+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.9
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.9
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.9
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.9
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.9
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.9
+SELECT a, TRUNCATE(a,2) FROM t1;
+a	TRUNCATE(a,2)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.99
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.99
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+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.99
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.99
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59.99
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.99
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.99
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.99
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.99
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.99
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.99
+SELECT a, TRUNCATE(a,3) FROM t1;
+a	TRUNCATE(a,3)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.999
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.999
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+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999
+SELECT a, TRUNCATE(a,4) FROM t1;
+a	TRUNCATE(a,4)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.9999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.9999
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+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.9999
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+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.9999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.9999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.9999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.9999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.9999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.9999
+SELECT a, TRUNCATE(a,5) FROM t1;
+a	TRUNCATE(a,5)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.99999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.99999
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.99999
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+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.99999
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.99999
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+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.99999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.99999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.99999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.99999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.99999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.99999
+SELECT a, TRUNCATE(a,6) FROM t1;
+a	TRUNCATE(a,6)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.999999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.999999
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+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.999999
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+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.999999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.999999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999999
+SELECT a, TRUNCATE(a,7) FROM t1;
+a	TRUNCATE(a,7)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.999999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.999999
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.999999
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+0000-01-01 23:59:59.999999	0000-01-01 23:59:59.999999
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59.999999
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59.999999
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.999999
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.999999
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59.999999
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.999999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.999999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999999
+SELECT a, TRUNCATE(a,-1) FROM t1;
+a	TRUNCATE(a,-1)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59
+0000-00-31 23:59:59.999999	0000-00-31 23:59:59
+0000-01-01 00:00:00.999999	0000-01-01 00:00:00
+0000-01-01 23:59:59.999999	0000-01-01 23:59:59
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+SELECT a, TRUNCATE(a,-6) FROM t1;
+a	TRUNCATE(a,-6)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59
+0000-00-31 23:59:59.999999	0000-00-31 23:59:59
+0000-01-01 00:00:00.999999	0000-01-01 00:00:00
+0000-01-01 23:59:59.999999	0000-01-01 23:59:59
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+SELECT a, ROUND(a) FROM t1;
+a	ROUND(a)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,0) FROM t1;
+a	ROUND(a,0)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,1) FROM t1;
+a	ROUND(a,1)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01.0
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01.0
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01.0
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01.0
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00.0
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00.0
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00.0
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00.0
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.0
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.0
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.9
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,2) FROM t1;
+a	ROUND(a,2)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01.00
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01.00
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01.00
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01.00
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00.00
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00.00
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00.00
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00.00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.00
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.99
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,3) FROM t1;
+a	ROUND(a,3)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01.000
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01.000
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01.000
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01.000
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00.000
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00.000
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00.000
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00.000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.000
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,4) FROM t1;
+a	ROUND(a,4)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01.0000
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01.0000
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01.0000
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01.0000
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00.0000
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00.0000
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00.0000
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00.0000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.0000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.0000
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.9999
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,5) FROM t1;
+a	ROUND(a,5)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01.00000
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01.00000
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01.00000
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01.00000
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00.00000
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00.00000
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00.00000
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00.00000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.00000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.00000
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.99999
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,6) FROM t1;
+a	ROUND(a,6)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.999999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.999999
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.999999
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59.999999
+0000-00-31 23:59:59.999999	0000-00-31 23:59:59.999999
+0000-01-01 00:00:00.999999	0000-01-01 00:00:00.999999
+0000-01-01 23:59:59.999999	0000-01-01 23:59:59.999999
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59.999999
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59.999999
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.999999
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.999999
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59.999999
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.999999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.999999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999999
+SELECT a, ROUND(a,7) FROM t1;
+a	ROUND(a,7)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:00.999999
+0000-00-00 23:59:59.999999	0000-00-00 23:59:59.999999
+0000-00-01 00:00:00.999999	0000-00-01 00:00:00.999999
+0000-00-01 23:59:59.999999	0000-00-01 23:59:59.999999
+0000-00-31 23:59:59.999999	0000-00-31 23:59:59.999999
+0000-01-01 00:00:00.999999	0000-01-01 00:00:00.999999
+0000-01-01 23:59:59.999999	0000-01-01 23:59:59.999999
+0000-01-31 23:59:59.999999	0000-01-31 23:59:59.999999
+0000-02-28 23:59:59.999999	0000-02-28 23:59:59.999999
+0000-12-31 23:59:59.999999	0000-12-31 23:59:59.999999
+0001-01-01 00:00:00.999999	0001-01-01 00:00:00.999999
+0001-02-28 23:59:59.999999	0001-02-28 23:59:59.999999
+0001-12-31 23:59:59.999999	0001-12-31 23:59:59.999999
+0004-02-28 23:59:59.999999	0004-02-28 23:59:59.999999
+0004-02-29 23:59:59.999999	0004-02-29 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59.999999
+SELECT a, ROUND(a,-1) FROM t1;
+a	ROUND(a,-1)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+SELECT a, ROUND(a,-6) FROM t1;
+a	ROUND(a,-6)
+0000-00-00 00:00:00.999999	0000-00-00 00:00:01
+0000-00-00 23:59:59.999999	NULL
+0000-00-01 00:00:00.999999	0000-00-01 00:00:01
+0000-00-01 23:59:59.999999	NULL
+0000-00-31 23:59:59.999999	NULL
+0000-01-01 00:00:00.999999	0000-01-01 00:00:01
+0000-01-01 23:59:59.999999	NULL
+0000-01-31 23:59:59.999999	NULL
+0000-02-28 23:59:59.999999	NULL
+0000-12-31 23:59:59.999999	NULL
+0001-01-01 00:00:00.999999	0001-01-01 00:00:01
+0001-02-28 23:59:59.999999	0001-03-01 00:00:00
+0001-12-31 23:59:59.999999	0002-01-01 00:00:00
+0004-02-28 23:59:59.999999	0004-02-29 00:00:00
+0004-02-29 23:59:59.999999	0004-03-01 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+9999-12-31 23:59:59.999999	9999-12-31 23:59:59
+Warnings:
+Warning	1411	Incorrect date value: '0000-00-00' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-00-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-01' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-01-31' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-02-28' for function round(datetime)
+Warning	1411	Incorrect date value: '0000-12-31' for function round(datetime)
+DROP TABLE t1;
+#
+# End of 10.4 tests
+#
diff --git a/mysql-test/main/type_datetime_hires.test b/mysql-test/main/type_datetime_hires.test
index d220a4601eb..ed9a85bcda3 100644
--- a/mysql-test/main/type_datetime_hires.test
+++ b/mysql-test/main/type_datetime_hires.test
@@ -79,3 +79,73 @@ INSERT INTO t1 VALUES ('2001-01-01 00:00:00'),('2000-00-00 00:00:00');
 SELECT UNIX_TIMESTAMP(a) FROM t1 ORDER BY 1;
 DROP TABLE t1;
 SET @@time_zone=DEFAULT;
+
+
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+--echo #
+
+CREATE TABLE t1 (a1 DATETIME(6), a2 DATETIME(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+  ROUND(a1) AS r1,
+  ROUND(a2) AS r2,
+  TRUNCATE(a1,0) AS t1,
+  TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+
+CREATE TABLE t1 (a DATETIME(6));
+INSERT INTO t1 VALUES
+('0000-00-00 00:00:00.999999'),
+('0000-00-00 23:59:59.999999'),
+('0000-00-01 00:00:00.999999'),
+('0000-00-01 23:59:59.999999'),
+('0000-00-31 23:59:59.999999'),
+('0000-01-01 00:00:00.999999'),
+('0000-01-01 23:59:59.999999'),
+('0000-01-31 23:59:59.999999'),
+('0000-02-28 23:59:59.999999'),
+('0000-12-31 23:59:59.999999'),
+('0001-01-01 00:00:00.999999'),
+('0001-02-28 23:59:59.999999'),
+('0001-12-31 23:59:59.999999'),
+('0004-02-28 23:59:59.999999'),
+('0004-02-29 23:59:59.999999'),
+('2000-02-29 23:59:59.999999'),
+('2000-12-31 23:59:59.999999'),
+('9999-12-31 23:59:59.999999');
+SELECT a, TRUNCATE(a,0) FROM t1;
+SELECT a, TRUNCATE(a,1) FROM t1;
+SELECT a, TRUNCATE(a,2) FROM t1;
+SELECT a, TRUNCATE(a,3) FROM t1;
+SELECT a, TRUNCATE(a,4) FROM t1;
+SELECT a, TRUNCATE(a,5) FROM t1;
+SELECT a, TRUNCATE(a,6) FROM t1;
+SELECT a, TRUNCATE(a,7) FROM t1;
+SELECT a, TRUNCATE(a,-1) FROM t1;
+SELECT a, TRUNCATE(a,-6) FROM t1;
+
+SELECT a, ROUND(a) FROM t1;
+SELECT a, ROUND(a,0) FROM t1;
+SELECT a, ROUND(a,1) FROM t1;
+SELECT a, ROUND(a,2) FROM t1;
+SELECT a, ROUND(a,3) FROM t1;
+SELECT a, ROUND(a,4) FROM t1;
+SELECT a, ROUND(a,5) FROM t1;
+SELECT a, ROUND(a,6) FROM t1;
+SELECT a, ROUND(a,7) FROM t1;
+SELECT a, ROUND(a,-1) FROM t1;
+SELECT a, ROUND(a,-6) FROM t1;
+
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.4 tests
+--echo #
diff --git a/mysql-test/main/type_time_hires.result b/mysql-test/main/type_time_hires.result
index ca19e9ed5bf..6122afcfc47 100644
--- a/mysql-test/main/type_time_hires.result
+++ b/mysql-test/main/type_time_hires.result
@@ -25,8 +25,8 @@ a
 03:04:05.789
 15:47:11.123
 838:59:59.999
-select truncate(a, 6) from t1;
-truncate(a, 6)
+select cast(a AS double(30,6)) from t1;
+cast(a AS double(30,6))
 2003.123000
 10203.456000
 30405.789062
@@ -359,3 +359,314 @@ drop table t1;
 select cast(1e-6 as time(6));
 cast(1e-6 as time(6))
 00:00:00.000001
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+#
+CREATE TABLE t1 (a1 TIME(6), a2 TIME(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+ROUND(a1) AS r1,
+ROUND(a2) AS r2,
+TRUNCATE(a1,0) AS t1,
+TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `r1` time DEFAULT NULL,
+  `r2` time NOT NULL,
+  `t1` time DEFAULT NULL,
+  `t2` time NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t2;
+DROP TABLE t1;
+CREATE TABLE t1 (a TIME(6));
+INSERT INTO t1 VALUES
+('-838:59:59.999999'),
+('-837:59:59.999999'),
+('-23:59:59.999999'),
+('-00:59:59.999999'),
+('-00:00:59.999999'),
+('00:00:00.999999'),
+('00:00:59.999999'),
+('00:59:59.999999'),
+('23:59:59.999999'),
+('837:59:59.999999'),
+('838:59:59.999999');
+SELECT a, TRUNCATE(a,0) FROM t1;
+a	TRUNCATE(a,0)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-837:59:59
+-23:59:59.999999	-23:59:59
+-00:59:59.999999	-00:59:59
+-00:00:59.999999	-00:00:59
+00:00:00.999999	00:00:00
+00:00:59.999999	00:00:59
+00:59:59.999999	00:59:59
+23:59:59.999999	23:59:59
+837:59:59.999999	837:59:59
+838:59:59.999999	838:59:59
+SELECT a, TRUNCATE(a,1) FROM t1;
+a	TRUNCATE(a,1)
+-838:59:59.999999	-838:59:59.9
+-837:59:59.999999	-837:59:59.9
+-23:59:59.999999	-23:59:59.9
+-00:59:59.999999	-00:59:59.9
+-00:00:59.999999	-00:00:59.9
+00:00:00.999999	00:00:00.9
+00:00:59.999999	00:00:59.9
+00:59:59.999999	00:59:59.9
+23:59:59.999999	23:59:59.9
+837:59:59.999999	837:59:59.9
+838:59:59.999999	838:59:59.9
+SELECT a, TRUNCATE(a,2) FROM t1;
+a	TRUNCATE(a,2)
+-838:59:59.999999	-838:59:59.99
+-837:59:59.999999	-837:59:59.99
+-23:59:59.999999	-23:59:59.99
+-00:59:59.999999	-00:59:59.99
+-00:00:59.999999	-00:00:59.99
+00:00:00.999999	00:00:00.99
+00:00:59.999999	00:00:59.99
+00:59:59.999999	00:59:59.99
+23:59:59.999999	23:59:59.99
+837:59:59.999999	837:59:59.99
+838:59:59.999999	838:59:59.99
+SELECT a, TRUNCATE(a,3) FROM t1;
+a	TRUNCATE(a,3)
+-838:59:59.999999	-838:59:59.999
+-837:59:59.999999	-837:59:59.999
+-23:59:59.999999	-23:59:59.999
+-00:59:59.999999	-00:59:59.999
+-00:00:59.999999	-00:00:59.999
+00:00:00.999999	00:00:00.999
+00:00:59.999999	00:00:59.999
+00:59:59.999999	00:59:59.999
+23:59:59.999999	23:59:59.999
+837:59:59.999999	837:59:59.999
+838:59:59.999999	838:59:59.999
+SELECT a, TRUNCATE(a,4) FROM t1;
+a	TRUNCATE(a,4)
+-838:59:59.999999	-838:59:59.9999
+-837:59:59.999999	-837:59:59.9999
+-23:59:59.999999	-23:59:59.9999
+-00:59:59.999999	-00:59:59.9999
+-00:00:59.999999	-00:00:59.9999
+00:00:00.999999	00:00:00.9999
+00:00:59.999999	00:00:59.9999
+00:59:59.999999	00:59:59.9999
+23:59:59.999999	23:59:59.9999
+837:59:59.999999	837:59:59.9999
+838:59:59.999999	838:59:59.9999
+SELECT a, TRUNCATE(a,5) FROM t1;
+a	TRUNCATE(a,5)
+-838:59:59.999999	-838:59:59.99999
+-837:59:59.999999	-837:59:59.99999
+-23:59:59.999999	-23:59:59.99999
+-00:59:59.999999	-00:59:59.99999
+-00:00:59.999999	-00:00:59.99999
+00:00:00.999999	00:00:00.99999
+00:00:59.999999	00:00:59.99999
+00:59:59.999999	00:59:59.99999
+23:59:59.999999	23:59:59.99999
+837:59:59.999999	837:59:59.99999
+838:59:59.999999	838:59:59.99999
+SELECT a, TRUNCATE(a,6) FROM t1;
+a	TRUNCATE(a,6)
+-838:59:59.999999	-838:59:59.999999
+-837:59:59.999999	-837:59:59.999999
+-23:59:59.999999	-23:59:59.999999
+-00:59:59.999999	-00:59:59.999999
+-00:00:59.999999	-00:00:59.999999
+00:00:00.999999	00:00:00.999999
+00:00:59.999999	00:00:59.999999
+00:59:59.999999	00:59:59.999999
+23:59:59.999999	23:59:59.999999
+837:59:59.999999	837:59:59.999999
+838:59:59.999999	838:59:59.999999
+SELECT a, TRUNCATE(a,7) FROM t1;
+a	TRUNCATE(a,7)
+-838:59:59.999999	-838:59:59.999999
+-837:59:59.999999	-837:59:59.999999
+-23:59:59.999999	-23:59:59.999999
+-00:59:59.999999	-00:59:59.999999
+-00:00:59.999999	-00:00:59.999999
+00:00:00.999999	00:00:00.999999
+00:00:59.999999	00:00:59.999999
+00:59:59.999999	00:59:59.999999
+23:59:59.999999	23:59:59.999999
+837:59:59.999999	837:59:59.999999
+838:59:59.999999	838:59:59.999999
+SELECT a, TRUNCATE(a,-1) FROM t1;
+a	TRUNCATE(a,-1)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-837:59:59
+-23:59:59.999999	-23:59:59
+-00:59:59.999999	-00:59:59
+-00:00:59.999999	-00:00:59
+00:00:00.999999	00:00:00
+00:00:59.999999	00:00:59
+00:59:59.999999	00:59:59
+23:59:59.999999	23:59:59
+837:59:59.999999	837:59:59
+838:59:59.999999	838:59:59
+SELECT a, TRUNCATE(a,-6) FROM t1;
+a	TRUNCATE(a,-6)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-837:59:59
+-23:59:59.999999	-23:59:59
+-00:59:59.999999	-00:59:59
+-00:00:59.999999	-00:00:59
+00:00:00.999999	00:00:00
+00:00:59.999999	00:00:59
+00:59:59.999999	00:59:59
+23:59:59.999999	23:59:59
+837:59:59.999999	837:59:59
+838:59:59.999999	838:59:59
+SELECT a, ROUND(a) FROM t1;
+a	ROUND(a)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-838:00:00
+-23:59:59.999999	-24:00:00
+-00:59:59.999999	-01:00:00
+-00:00:59.999999	-00:01:00
+00:00:00.999999	00:00:01
+00:00:59.999999	00:01:00
+00:59:59.999999	01:00:00
+23:59:59.999999	24:00:00
+837:59:59.999999	838:00:00
+838:59:59.999999	838:59:59
+SELECT a, ROUND(a,0) FROM t1;
+a	ROUND(a,0)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-838:00:00
+-23:59:59.999999	-24:00:00
+-00:59:59.999999	-01:00:00
+-00:00:59.999999	-00:01:00
+00:00:00.999999	00:00:01
+00:00:59.999999	00:01:00
+00:59:59.999999	01:00:00
+23:59:59.999999	24:00:00
+837:59:59.999999	838:00:00
+838:59:59.999999	838:59:59
+SELECT a, ROUND(a,1) FROM t1;
+a	ROUND(a,1)
+-838:59:59.999999	-838:59:59.9
+-837:59:59.999999	-838:00:00.0
+-23:59:59.999999	-24:00:00.0
+-00:59:59.999999	-01:00:00.0
+-00:00:59.999999	-00:01:00.0
+00:00:00.999999	00:00:01.0
+00:00:59.999999	00:01:00.0
+00:59:59.999999	01:00:00.0
+23:59:59.999999	24:00:00.0
+837:59:59.999999	838:00:00.0
+838:59:59.999999	838:59:59.9
+SELECT a, ROUND(a,2) FROM t1;
+a	ROUND(a,2)
+-838:59:59.999999	-838:59:59.99
+-837:59:59.999999	-838:00:00.00
+-23:59:59.999999	-24:00:00.00
+-00:59:59.999999	-01:00:00.00
+-00:00:59.999999	-00:01:00.00
+00:00:00.999999	00:00:01.00
+00:00:59.999999	00:01:00.00
+00:59:59.999999	01:00:00.00
+23:59:59.999999	24:00:00.00
+837:59:59.999999	838:00:00.00
+838:59:59.999999	838:59:59.99
+SELECT a, ROUND(a,3) FROM t1;
+a	ROUND(a,3)
+-838:59:59.999999	-838:59:59.999
+-837:59:59.999999	-838:00:00.000
+-23:59:59.999999	-24:00:00.000
+-00:59:59.999999	-01:00:00.000
+-00:00:59.999999	-00:01:00.000
+00:00:00.999999	00:00:01.000
+00:00:59.999999	00:01:00.000
+00:59:59.999999	01:00:00.000
+23:59:59.999999	24:00:00.000
+837:59:59.999999	838:00:00.000
+838:59:59.999999	838:59:59.999
+SELECT a, ROUND(a,4) FROM t1;
+a	ROUND(a,4)
+-838:59:59.999999	-838:59:59.9999
+-837:59:59.999999	-838:00:00.0000
+-23:59:59.999999	-24:00:00.0000
+-00:59:59.999999	-01:00:00.0000
+-00:00:59.999999	-00:01:00.0000
+00:00:00.999999	00:00:01.0000
+00:00:59.999999	00:01:00.0000
+00:59:59.999999	01:00:00.0000
+23:59:59.999999	24:00:00.0000
+837:59:59.999999	838:00:00.0000
+838:59:59.999999	838:59:59.9999
+SELECT a, ROUND(a,5) FROM t1;
+a	ROUND(a,5)
+-838:59:59.999999	-838:59:59.99999
+-837:59:59.999999	-838:00:00.00000
+-23:59:59.999999	-24:00:00.00000
+-00:59:59.999999	-01:00:00.00000
+-00:00:59.999999	-00:01:00.00000
+00:00:00.999999	00:00:01.00000
+00:00:59.999999	00:01:00.00000
+00:59:59.999999	01:00:00.00000
+23:59:59.999999	24:00:00.00000
+837:59:59.999999	838:00:00.00000
+838:59:59.999999	838:59:59.99999
+SELECT a, ROUND(a,6) FROM t1;
+a	ROUND(a,6)
+-838:59:59.999999	-838:59:59.999999
+-837:59:59.999999	-837:59:59.999999
+-23:59:59.999999	-23:59:59.999999
+-00:59:59.999999	-00:59:59.999999
+-00:00:59.999999	-00:00:59.999999
+00:00:00.999999	00:00:00.999999
+00:00:59.999999	00:00:59.999999
+00:59:59.999999	00:59:59.999999
+23:59:59.999999	23:59:59.999999
+837:59:59.999999	837:59:59.999999
+838:59:59.999999	838:59:59.999999
+SELECT a, ROUND(a,7) FROM t1;
+a	ROUND(a,7)
+-838:59:59.999999	-838:59:59.999999
+-837:59:59.999999	-837:59:59.999999
+-23:59:59.999999	-23:59:59.999999
+-00:59:59.999999	-00:59:59.999999
+-00:00:59.999999	-00:00:59.999999
+00:00:00.999999	00:00:00.999999
+00:00:59.999999	00:00:59.999999
+00:59:59.999999	00:59:59.999999
+23:59:59.999999	23:59:59.999999
+837:59:59.999999	837:59:59.999999
+838:59:59.999999	838:59:59.999999
+SELECT a, ROUND(a,-1) FROM t1;
+a	ROUND(a,-1)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-838:00:00
+-23:59:59.999999	-24:00:00
+-00:59:59.999999	-01:00:00
+-00:00:59.999999	-00:01:00
+00:00:00.999999	00:00:01
+00:00:59.999999	00:01:00
+00:59:59.999999	01:00:00
+23:59:59.999999	24:00:00
+837:59:59.999999	838:00:00
+838:59:59.999999	838:59:59
+SELECT a, ROUND(a,-6) FROM t1;
+a	ROUND(a,-6)
+-838:59:59.999999	-838:59:59
+-837:59:59.999999	-838:00:00
+-23:59:59.999999	-24:00:00
+-00:59:59.999999	-01:00:00
+-00:00:59.999999	-00:01:00
+00:00:00.999999	00:00:01
+00:00:59.999999	00:01:00
+00:59:59.999999	01:00:00
+23:59:59.999999	24:00:00
+837:59:59.999999	838:00:00
+838:59:59.999999	838:59:59
+DROP TABLE t1;
+SET time_zone=DEFAULT;
diff --git a/mysql-test/main/type_time_hires.test b/mysql-test/main/type_time_hires.test
index 3785a23f1eb..0949738e949 100644
--- a/mysql-test/main/type_time_hires.test
+++ b/mysql-test/main/type_time_hires.test
@@ -10,3 +10,66 @@ select min(a - interval 1 hour), max(a - interval 1 hour) from t1 where a < 0;
 drop table t1;
 
 select cast(1e-6 as time(6));
+
+
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+--echo #
+
+CREATE TABLE t1 (a1 TIME(6), a2 TIME(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+  ROUND(a1) AS r1,
+  ROUND(a2) AS r2,
+  TRUNCATE(a1,0) AS t1,
+  TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+
+CREATE TABLE t1 (a TIME(6));
+INSERT INTO t1 VALUES
+('-838:59:59.999999'),
+('-837:59:59.999999'),
+('-23:59:59.999999'),
+('-00:59:59.999999'),
+('-00:00:59.999999'),
+('00:00:00.999999'),
+('00:00:59.999999'),
+('00:59:59.999999'),
+('23:59:59.999999'),
+('837:59:59.999999'),
+('838:59:59.999999');
+
+
+SELECT a, TRUNCATE(a,0) FROM t1;
+SELECT a, TRUNCATE(a,1) FROM t1;
+SELECT a, TRUNCATE(a,2) FROM t1;
+SELECT a, TRUNCATE(a,3) FROM t1;
+SELECT a, TRUNCATE(a,4) FROM t1;
+SELECT a, TRUNCATE(a,5) FROM t1;
+SELECT a, TRUNCATE(a,6) FROM t1;
+SELECT a, TRUNCATE(a,7) FROM t1;
+SELECT a, TRUNCATE(a,-1) FROM t1;
+SELECT a, TRUNCATE(a,-6) FROM t1;
+
+SELECT a, ROUND(a) FROM t1;
+SELECT a, ROUND(a,0) FROM t1;
+SELECT a, ROUND(a,1) FROM t1;
+SELECT a, ROUND(a,2) FROM t1;
+SELECT a, ROUND(a,3) FROM t1;
+SELECT a, ROUND(a,4) FROM t1;
+SELECT a, ROUND(a,5) FROM t1;
+SELECT a, ROUND(a,6) FROM t1;
+SELECT a, ROUND(a,7) FROM t1;
+SELECT a, ROUND(a,-1) FROM t1;
+SELECT a, ROUND(a,-6) FROM t1;
+
+DROP TABLE t1;
+
+SET time_zone=DEFAULT;
diff --git a/mysql-test/main/type_timestamp_hires.result b/mysql-test/main/type_timestamp_hires.result
index fa6adc075ed..dc69aa36b0f 100644
--- a/mysql-test/main/type_timestamp_hires.result
+++ b/mysql-test/main/type_timestamp_hires.result
@@ -17,8 +17,8 @@ a
 2010-12-11 01:02:03.456
 2010-12-11 03:04:05.789
 2010-12-11 15:47:11.123
-select truncate(a, 6) from t1;
-truncate(a, 6)
+select cast(a AS double(30,6)) from t1;
+cast(a AS double(30,6))
 0.000000
 20101211002003.120000
 20101211010203.457031
@@ -333,3 +333,298 @@ t1	CREATE TABLE `t1` (
   `a` timestamp(5) NOT NULL DEFAULT '0000-00-00 00:00:00.00000' ON UPDATE current_timestamp(5)
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+#
+# ROUND(timestamp) and TRUNCATE(timestamp) currently return DATETIME.
+# This may change in the future to return TIMESTAMP.
+CREATE TABLE t1 (a1 TIMESTAMP(6) NULL DEFAULT '2001-01-01 00:00:00', a2 TIMESTAMP(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+ROUND(a1) AS r1,
+ROUND(a2) AS r2,
+TRUNCATE(a1,0) AS t1,
+TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `r1` datetime DEFAULT NULL,
+  `r2` datetime DEFAULT NULL,
+  `t1` datetime DEFAULT NULL,
+  `t2` datetime NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t2;
+DROP TABLE t1;
+SET time_zone='+00:00';
+CREATE TABLE t1 (a TIMESTAMP(6));
+INSERT INTO t1 VALUES
+('1970-01-01 00:00:01.999999'),
+('2000-01-01 00:00:00.999999'),
+('2000-01-01 23:59:59.999999'),
+('2000-02-29 23:59:59.999999'),
+('2000-12-31 23:59:59.999999'),
+('2001-01-01 00:00:00.999999'),
+('2001-01-01 23:59:59.999999'),
+('2001-02-28 23:59:59.999999'),
+('2001-12-31 23:59:59.999999'),
+('2038-01-19 03:14:07.999999');
+SELECT a, TRUNCATE(a,0) FROM t1;
+a	TRUNCATE(a,0)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07
+SELECT a, TRUNCATE(a,1) FROM t1;
+a	TRUNCATE(a,1)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.9
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.9
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.9
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.9
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.9
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.9
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.9
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.9
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.9
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.9
+SELECT a, TRUNCATE(a,2) FROM t1;
+a	TRUNCATE(a,2)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.99
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.99
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.99
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.99
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.99
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.99
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.99
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.99
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.99
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.99
+SELECT a, TRUNCATE(a,3) FROM t1;
+a	TRUNCATE(a,3)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.999
+SELECT a, TRUNCATE(a,4) FROM t1;
+a	TRUNCATE(a,4)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.9999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.9999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.9999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.9999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.9999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.9999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.9999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.9999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.9999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.9999
+SELECT a, TRUNCATE(a,5) FROM t1;
+a	TRUNCATE(a,5)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.99999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.99999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.99999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.99999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.99999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.99999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.99999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.99999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.99999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.99999
+SELECT a, TRUNCATE(a,6) FROM t1;
+a	TRUNCATE(a,6)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.999999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.999999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.999999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.999999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.999999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.999999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.999999
+SELECT a, TRUNCATE(a,7) FROM t1;
+a	TRUNCATE(a,7)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.999999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.999999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.999999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.999999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.999999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.999999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.999999
+SELECT a, TRUNCATE(a,-1) FROM t1;
+a	TRUNCATE(a,-1)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07
+SELECT a, TRUNCATE(a,-6) FROM t1;
+a	TRUNCATE(a,-6)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07
+SELECT a, ROUND(a) FROM t1;
+a	ROUND(a)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08
+SELECT a, ROUND(a,0) FROM t1;
+a	ROUND(a,0)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08
+SELECT a, ROUND(a,1) FROM t1;
+a	ROUND(a,1)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02.0
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01.0
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00.0
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.0
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.0
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01.0
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00.0
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00.0
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00.0
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08.0
+SELECT a, ROUND(a,2) FROM t1;
+a	ROUND(a,2)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02.00
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01.00
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00.00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.00
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01.00
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00.00
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00.00
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00.00
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08.00
+SELECT a, ROUND(a,3) FROM t1;
+a	ROUND(a,3)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02.000
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01.000
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00.000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.000
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01.000
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00.000
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00.000
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00.000
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08.000
+SELECT a, ROUND(a,4) FROM t1;
+a	ROUND(a,4)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02.0000
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01.0000
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00.0000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.0000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.0000
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01.0000
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00.0000
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00.0000
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00.0000
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08.0000
+SELECT a, ROUND(a,5) FROM t1;
+a	ROUND(a,5)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02.00000
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01.00000
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00.00000
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00.00000
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00.00000
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01.00000
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00.00000
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00.00000
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00.00000
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08.00000
+SELECT a, ROUND(a,6) FROM t1;
+a	ROUND(a,6)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.999999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.999999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.999999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.999999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.999999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.999999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.999999
+SELECT a, ROUND(a,7) FROM t1;
+a	ROUND(a,7)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:01.999999
+2000-01-01 00:00:00.999999	2000-01-01 00:00:00.999999
+2000-01-01 23:59:59.999999	2000-01-01 23:59:59.999999
+2000-02-29 23:59:59.999999	2000-02-29 23:59:59.999999
+2000-12-31 23:59:59.999999	2000-12-31 23:59:59.999999
+2001-01-01 00:00:00.999999	2001-01-01 00:00:00.999999
+2001-01-01 23:59:59.999999	2001-01-01 23:59:59.999999
+2001-02-28 23:59:59.999999	2001-02-28 23:59:59.999999
+2001-12-31 23:59:59.999999	2001-12-31 23:59:59.999999
+2038-01-19 03:14:07.999999	2038-01-19 03:14:07.999999
+SELECT a, ROUND(a,-1) FROM t1;
+a	ROUND(a,-1)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08
+SELECT a, ROUND(a,-6) FROM t1;
+a	ROUND(a,-6)
+1970-01-01 00:00:01.999999	1970-01-01 00:00:02
+2000-01-01 00:00:00.999999	2000-01-01 00:00:01
+2000-01-01 23:59:59.999999	2000-01-02 00:00:00
+2000-02-29 23:59:59.999999	2000-03-01 00:00:00
+2000-12-31 23:59:59.999999	2001-01-01 00:00:00
+2001-01-01 00:00:00.999999	2001-01-01 00:00:01
+2001-01-01 23:59:59.999999	2001-01-02 00:00:00
+2001-02-28 23:59:59.999999	2001-03-01 00:00:00
+2001-12-31 23:59:59.999999	2002-01-01 00:00:00
+2038-01-19 03:14:07.999999	2038-01-19 03:14:08
+DROP TABLE t1;
+SET time_zone=DEFAULT;
+#
+# End of 10.4 tests
+#
diff --git a/mysql-test/main/type_timestamp_hires.test b/mysql-test/main/type_timestamp_hires.test
index 0b05f81ef42..f2e765d09fe 100644
--- a/mysql-test/main/type_timestamp_hires.test
+++ b/mysql-test/main/type_timestamp_hires.test
@@ -40,3 +40,73 @@ show create table t1;
 create or replace table t1 (a timestamp(5) on update current_timestamp(6));
 show create table t1;
 drop table t1;
+
+
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-20397 Support TIMESTAMP, DATETIME, TIME in ROUND() and TRUNCATE()
+--echo #
+
+--echo # ROUND(timestamp) and TRUNCATE(timestamp) currently return DATETIME.
+--echo # This may change in the future to return TIMESTAMP.
+
+CREATE TABLE t1 (a1 TIMESTAMP(6) NULL DEFAULT '2001-01-01 00:00:00', a2 TIMESTAMP(6) NOT NULL);
+CREATE TABLE t2 AS SELECT
+  ROUND(a1) AS r1,
+  ROUND(a2) AS r2,
+  TRUNCATE(a1,0) AS t1,
+  TRUNCATE(a2,0) AS t2
+FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t2;
+DROP TABLE t1;
+
+
+SET time_zone='+00:00';
+
+CREATE TABLE t1 (a TIMESTAMP(6));
+INSERT INTO t1 VALUES
+('1970-01-01 00:00:01.999999'),
+('2000-01-01 00:00:00.999999'),
+('2000-01-01 23:59:59.999999'),
+('2000-02-29 23:59:59.999999'),
+('2000-12-31 23:59:59.999999'),
+('2001-01-01 00:00:00.999999'),
+('2001-01-01 23:59:59.999999'),
+('2001-02-28 23:59:59.999999'),
+('2001-12-31 23:59:59.999999'),
+('2038-01-19 03:14:07.999999');
+
+SELECT a, TRUNCATE(a,0) FROM t1;
+SELECT a, TRUNCATE(a,1) FROM t1;
+SELECT a, TRUNCATE(a,2) FROM t1;
+SELECT a, TRUNCATE(a,3) FROM t1;
+SELECT a, TRUNCATE(a,4) FROM t1;
+SELECT a, TRUNCATE(a,5) FROM t1;
+SELECT a, TRUNCATE(a,6) FROM t1;
+SELECT a, TRUNCATE(a,7) FROM t1;
+SELECT a, TRUNCATE(a,-1) FROM t1;
+SELECT a, TRUNCATE(a,-6) FROM t1;
+
+SELECT a, ROUND(a) FROM t1;
+SELECT a, ROUND(a,0) FROM t1;
+SELECT a, ROUND(a,1) FROM t1;
+SELECT a, ROUND(a,2) FROM t1;
+SELECT a, ROUND(a,3) FROM t1;
+SELECT a, ROUND(a,4) FROM t1;
+SELECT a, ROUND(a,5) FROM t1;
+SELECT a, ROUND(a,6) FROM t1;
+SELECT a, ROUND(a,7) FROM t1;
+SELECT a, ROUND(a,-1) FROM t1;
+SELECT a, ROUND(a,-6) FROM t1;
+
+DROP TABLE t1;
+
+SET time_zone=DEFAULT;
+
+--echo #
+--echo # End of 10.4 tests
+--echo #
diff --git a/sql/item_func.cc b/sql/item_func.cc
index ce01ef1a686..ced1d69caa9 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2338,6 +2338,42 @@ void Item_func_round::fix_arg_double()
 }
 
 
+void Item_func_round::fix_arg_temporal(const Type_handler *h,
+                                       uint int_part_length)
+{
+  set_handler(h);
+  if (args[1]->const_item() && !args[1]->is_expensive())
+  {
+    Longlong_hybrid_null dec= args[1]->to_longlong_hybrid_null();
+    fix_attributes_temporal(int_part_length,
+                            dec.is_null() ? args[0]->decimals :
+                            dec.to_uint(TIME_SECOND_PART_DIGITS));
+  }
+  else
+    fix_attributes_temporal(int_part_length, args[0]->decimals);
+}
+
+
+void Item_func_round::fix_arg_time()
+{
+  fix_arg_temporal(&type_handler_time2, MIN_TIME_WIDTH);
+}
+
+
+void Item_func_round::fix_arg_datetime()
+{
+  /*
+    Day increment operations are not supported for '0000-00-00',
+    see get_date_from_daynr() for details. Therefore, expressions like
+      ROUND('0000-00-00 23:59:59.999999')
+    return NULL.
+  */
+  if (!truncate)
+    maybe_null= true;
+  fix_arg_temporal(&type_handler_datetime2, MAX_DATETIME_WIDTH);
+}
+
+
 void Item_func_round::fix_arg_int()
 {
   if (args[1]->const_item())
@@ -2477,6 +2513,36 @@ my_decimal *Item_func_round::decimal_op(my_decimal *decimal_value)
 }
 
 
+bool Item_func_round::time_op(THD *thd, MYSQL_TIME *to)
+{
+  DBUG_ASSERT(args[0]->type_handler()->mysql_timestamp_type() ==
+              MYSQL_TIMESTAMP_TIME);
+  Time::Options opt(Time::default_flags_for_get_date(),
+                    truncate ? TIME_FRAC_TRUNCATE : TIME_FRAC_ROUND,
+                    Time::DATETIME_TO_TIME_DISALLOW);
+  Longlong_hybrid_null dec= args[1]->to_longlong_hybrid_null();
+  Time *tm= new (to) Time(thd, args[0], opt,
+                          dec.to_uint(TIME_SECOND_PART_DIGITS));
+  null_value= !tm->is_valid_time() || dec.is_null();
+  DBUG_ASSERT(maybe_null || !null_value);
+  return null_value;
+}
+
+
+bool Item_func_round::date_op(THD *thd, MYSQL_TIME *to, date_mode_t fuzzydate)
+{
+  DBUG_ASSERT(args[0]->type_handler()->mysql_timestamp_type() ==
+              MYSQL_TIMESTAMP_DATETIME);
+  Datetime::Options opt(thd, truncate ? TIME_FRAC_TRUNCATE : TIME_FRAC_ROUND);
+  Longlong_hybrid_null dec= args[1]->to_longlong_hybrid_null();
+  Datetime *tm= new (to) Datetime(thd, args[0], opt,
+                                  dec.to_uint(TIME_SECOND_PART_DIGITS));
+  null_value= !tm->is_valid_datetime() || dec.is_null();
+  DBUG_ASSERT(maybe_null || !null_value);
+  return null_value;
+}
+
+
 void Item_func_rand::seed_random(Item *arg)
 {
   /*
diff --git a/sql/item_func.h b/sql/item_func.h
index 610adb4bb46..eaa5410dea2 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -1700,21 +1700,36 @@ public:
 
 /* This handles round and truncate */
 
-class Item_func_round :public Item_func_numhybrid
+class Item_func_round :public Item_func_hybrid_field_type
 {
   bool truncate;
   void fix_length_and_dec_decimal(uint decimals_to_set);
   void fix_length_and_dec_double(uint decimals_to_set);
 public:
   Item_func_round(THD *thd, Item *a, Item *b, bool trunc_arg)
-    :Item_func_numhybrid(thd, a, b), truncate(trunc_arg) {}
+    :Item_func_hybrid_field_type(thd, a, b), truncate(trunc_arg) {}
   const char *func_name() const { return truncate ? "truncate" : "round"; }
   double real_op();
   longlong int_op();
   my_decimal *decimal_op(my_decimal *);
+  bool date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate);
+  bool time_op(THD *thd, MYSQL_TIME *ltime);
+  bool native_op(THD *thd, Native *to)
+  {
+    DBUG_ASSERT(0);
+    return true;
+  }
+  String *str_op(String *str)
+  {
+    DBUG_ASSERT(0);
+    return NULL;
+  }
   void fix_arg_decimal();
   void fix_arg_int();
   void fix_arg_double();
+  void fix_arg_time();
+  void fix_arg_datetime();
+  void fix_arg_temporal(const Type_handler *h, uint int_part_length);
   bool fix_length_and_dec()
   {
     return args[0]->type_handler()->Item_func_round_fix_length_and_dec(this);
diff --git a/sql/sql_time.cc b/sql/sql_time.cc
index c64995fa3d6..b128a7f7291 100644
--- a/sql/sql_time.cc
+++ b/sql/sql_time.cc
@@ -914,7 +914,7 @@ void make_truncated_value_warning(THD *thd,
 #define GET_PART(X, N) X % N ## LL; X/= N ## LL
 
 bool date_add_interval(THD *thd, MYSQL_TIME *ltime, interval_type int_type,
-                       const INTERVAL &interval)
+                       const INTERVAL &interval, bool push_warn)
 {
   long period, sign;
 
@@ -1027,6 +1027,7 @@ bool date_add_interval(THD *thd, MYSQL_TIME *ltime, interval_type int_type,
     return 0;                                   // Ok
 
 invalid_date:
+  if (push_warn)
   {
     push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                         ER_DATETIME_FUNCTION_OVERFLOW,
diff --git a/sql/sql_time.h b/sql/sql_time.h
index 25980d6417c..fe9697adf67 100644
--- a/sql/sql_time.h
+++ b/sql/sql_time.h
@@ -92,7 +92,7 @@ bool my_TIME_to_str(const MYSQL_TIME *ltime, String *str, uint dec);
 
 /* MYSQL_TIME operations */
 bool date_add_interval(THD *thd, MYSQL_TIME *ltime, interval_type int_type,
-                       const INTERVAL &interval);
+                       const INTERVAL &interval, bool push_warn= true);
 bool calc_time_diff(const MYSQL_TIME *l_time1, const MYSQL_TIME *l_time2,
                     int l_sign, ulonglong *seconds_out, ulong *microseconds_out);
 int append_interval(String *str, interval_type int_type,
diff --git a/sql/sql_type.cc b/sql/sql_type.cc
index 6653b8b1a3f..8b382773f7a 100644
--- a/sql/sql_type.cc
+++ b/sql/sql_type.cc
@@ -953,10 +953,21 @@ bool Temporal::datetime_add_nanoseconds_or_invalidate(THD *thd, int *warn, ulong
   INTERVAL interval;
   memset(&interval, 0, sizeof(interval));
   interval.hour= 1;
-  /* date_add_interval cannot handle bad dates */
-  if (check_date(TIME_NO_ZERO_IN_DATE | TIME_NO_ZERO_DATE, warn) ||
-      date_add_interval(thd, this, INTERVAL_HOUR, interval))
+  /*
+    date_add_interval cannot handle bad dates with zero YYYY or MM.
+    Note, check_date(NO_ZERO_XX) does not check YYYY against zero,
+    so let's additionally check it.
+  */
+  if (year == 0 ||
+      check_date(TIME_NO_ZERO_IN_DATE | TIME_NO_ZERO_DATE, warn) ||
+      date_add_interval(thd, this, INTERVAL_HOUR, interval, false/*no warn*/))
   {
+    char buf[MAX_DATE_STRING_REP_LENGTH];
+    my_date_to_str(this, buf);
+    push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                        ER_WRONG_VALUE_FOR_TYPE,
+                        ER_THD(thd, ER_WRONG_VALUE_FOR_TYPE),
+                        "date", buf, "round(datetime)");
     make_from_out_of_range(warn);
     return true;
   }
@@ -5620,6 +5631,30 @@ bool Type_handler_temporal_result::
 }
 
 
+bool Type_handler_time_common::
+       Item_func_round_fix_length_and_dec(Item_func_round *item) const
+{
+  item->fix_arg_time();
+  return false;
+}
+
+
+bool Type_handler_datetime_common::
+       Item_func_round_fix_length_and_dec(Item_func_round *item) const
+{
+  item->fix_arg_datetime();
+  return false;
+}
+
+
+bool Type_handler_timestamp_common::
+       Item_func_round_fix_length_and_dec(Item_func_round *item) const
+{
+  item->fix_arg_datetime();
+  return false;
+}
+
+
 bool Type_handler_string_result::
        Item_func_round_fix_length_and_dec(Item_func_round *item) const
 {
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 0f270ce9d5d..4b87d6cc989 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -5281,6 +5281,7 @@ public:
   bool Item_func_min_max_get_date(THD *thd, Item_func_min_max*,
                                   MYSQL_TIME *, date_mode_t fuzzydate) const;
   longlong Item_func_between_val_int(Item_func_between *func) const;
+  bool Item_func_round_fix_length_and_dec(Item_func_round *) const;
   Item *make_const_item_for_comparison(THD *, Item *src, const Item *cmp) const;
   bool set_comparator_func(Arg_comparator *cmp) const;
   cmp_item *make_cmp_item(THD *thd, CHARSET_INFO *cs) const;
@@ -5507,6 +5508,7 @@ public:
   longlong Item_func_min_max_val_int(Item_func_min_max *) const;
   my_decimal *Item_func_min_max_val_decimal(Item_func_min_max *,
                                             my_decimal *) const;
+  bool Item_func_round_fix_length_and_dec(Item_func_round *) const;
   bool Item_hybrid_func_fix_attributes(THD *thd,
                                        const char *name,
                                        Type_handler_hybrid_field_type *,
@@ -5608,6 +5610,7 @@ public:
   bool Item_param_val_native(THD *thd, Item_param *item, Native *to) const;
   int cmp_native(const Native &a, const Native &b) const;
   longlong Item_func_between_val_int(Item_func_between *func) const;
+  bool Item_func_round_fix_length_and_dec(Item_func_round *) const;
   cmp_item *make_cmp_item(THD *thd, CHARSET_INFO *cs) const;
   in_vector *make_in_vector(THD *thd, const Item_func_in *f, uint nargs) const;
   void make_sort_key(uchar *to, Item *item, const SORT_FIELD_ATTR *sort_field,