Bug #26881946: INCORRECT BEHAVIOR WITH "VALUES"

Issue:
------
VALUES doesn't have a type() function and is considered a
Item_field.

Solution for 5.7:
-----------------
Add a new type() function for Item_values_insert.

On 8.0 and trunk it was fixed by Mithun's Bug#19601973.

Solution for 5.6:
-----------------
Additionally Bug#17458914 is backported.

This will address the problem of using VALUES() in
INSERT ... ON DUPLICATE KEY UPDATE. Create a field object
only if it is in the UPDATE clause, else return a NULL
item.

This will also address the problems mentioned in
Bug#14789787 and Bug#16756402.

Solution for 5.5:
-----------------
As mentioned above Bug#17458914 is backported.

Additionally Bug#14786324 is also backported.

When VALUES() is detected outside its meaningful place,
it should be treated as NULL and is thus replaced with a
Field_null object, with the same name as the original
field.

Fields with type NULL are generally not handled well inside
the server (e.g Innodb will not accept them and it is
impossible to create them in regular tables). So create a
new const NULL item instead.

1 files changed, 3 insertions, 3 deletions

diff --git a/mysql-test/r/insert_update.result b/mysql-test/r/insert_update.result
index a285810b78b..31e7b253267 100644
--- a/mysql-test/r/insert_update.result
+++ b/mysql-test/r/insert_update.result
@@ -60,12 +60,12 @@ explain extended SELECT *, VALUES(a) FROM t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c`,values(`test`.`t1`.`a`) AS `VALUES(a)` from `test`.`t1`
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c`,NULL AS `VALUES(a)` from `test`.`t1`
 explain extended select * from t1 where values(a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c` from `test`.`t1` where values(`test`.`t1`.`a`)
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c` from `test`.`t1` where 0
 DROP TABLE t1;
 create table t1(a int primary key, b int);
 insert into t1 values(1,1),(2,2),(3,3),(4,4),(5,5);