MDEV-4439 ALTER TABLE .. [ADD|DROP] FOREIGN KEY IF [NOT] EXISTS does not work if constraint name is not used.

  Patches for server and the Innodb engine.
  Server is fixed so it does nothing if no indexes left to alter.
  Innodb parser is fixed so it looks for the IF [NOT] EXISTS option in a string.
  Another change is that it uses the index name for the internal dictionary.
  Prior to that it only used the CONSTRAINT name for it.

1 files changed, 40 insertions, 1 deletions

diff --git a/mysql-test/t/alter_table.test b/mysql-test/t/alter_table.test
index 2053e2d9d59..3050fc0378d 100644
--- a/mysql-test/t/alter_table.test
+++ b/mysql-test/t/alter_table.test
@@ -1258,7 +1258,7 @@ CREATE TABLE t1 (
   id INT(11) NOT NULL,
   x_param INT(11) DEFAULT NULL,
   PRIMARY KEY (id)
-);
+) ENGINE=MYISAM;
 
 ALTER TABLE t1 ADD COLUMN IF NOT EXISTS id INT,
                ADD COLUMN IF NOT EXISTS lol INT AFTER id;
@@ -1277,6 +1277,45 @@ CREATE INDEX IF NOT EXISTS x_param1 ON t1(x_param);
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+CREATE TABLE t1 (
+  id INT(11) NOT NULL,
+  x_param INT(11) DEFAULT NULL,
+  PRIMARY KEY (id)
+) ENGINE=INNODB;
+
+CREATE TABLE t2 (
+  id INT(11) NOT NULL) ENGINE=INNODB;
+
+ALTER TABLE t1 ADD COLUMN IF NOT EXISTS id INT,
+               ADD COLUMN IF NOT EXISTS lol INT AFTER id;
+ALTER TABLE t1 ADD COLUMN IF NOT EXISTS lol INT AFTER id;
+ALTER TABLE t1 DROP COLUMN IF EXISTS lol;
+ALTER TABLE t1 DROP COLUMN IF EXISTS lol;
+
+ALTER TABLE t1 ADD KEY IF NOT EXISTS x_param(x_param);
+ALTER TABLE t1 ADD KEY IF NOT EXISTS x_param(x_param);
+ALTER TABLE t1 MODIFY IF EXISTS lol INT;
+
+DROP INDEX IF EXISTS x_param ON t1;
+DROP INDEX IF EXISTS x_param ON t1;
+CREATE INDEX IF NOT EXISTS x_param1 ON t1(x_param);
+CREATE INDEX IF NOT EXISTS x_param1 ON t1(x_param);
+SHOW CREATE TABLE t1;
+
+ALTER TABLE t2 ADD FOREIGN KEY IF NOT EXISTS fk(id) REFERENCES t1(id);
+ALTER TABLE t2 ADD FOREIGN KEY IF NOT EXISTS fk(id) REFERENCES t1(id);
+ALTER TABLE t2 DROP FOREIGN KEY IF EXISTS fk;
+ALTER TABLE t2 DROP FOREIGN KEY IF EXISTS fk;
+SHOW CREATE TABLE t2;
+ALTER TABLE t2 ADD FOREIGN KEY (id) REFERENCES t1(id);
+ALTER TABLE t2 ADD FOREIGN KEY IF NOT EXISTS t2_ibfk_1(id) REFERENCES t1(id);
+ALTER TABLE t2 DROP FOREIGN KEY IF EXISTS t2_ibfk_1;
+ALTER TABLE t2 DROP FOREIGN KEY IF EXISTS t2_ibfk_1;
+SHOW CREATE TABLE t2;
+
+DROP TABLE t2;
+DROP TABLE t1;
+
 --echo #
 --echo # Bug#11938817 ALTER BEHAVIOR DIFFERENT THEN DOCUMENTED
 --echo #