2 files changed, 76 insertions, 0 deletions
diff --git a/mysql-test/r/if_exists.result b/mysql-test/r/if_exists.result
new file mode 100644
index 00000000000..4cb718b9cfc
--- /dev/null
+++ b/mysql-test/r/if_exists.result
@@ -0,0 +1,43 @@
+CREATE TABLE t1 (a INT, b INT) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP COLUMN b;
+Warnings:
+Note	1091	Can't DROP 'fk'; check that column/key exists
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT) ENGINE=InnoDB;
+ALTER TABLE t1 DROP INDEX IF EXISTS fk, DROP COLUMN b;
+Warnings:
+Note	1091	Can't DROP 'fk'; check that column/key exists
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT, c INT, KEY(c)) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP COLUMN c;
+Warnings:
+Note	1091	Can't DROP 'fk'; check that column/key exists
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `b` int(11) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT, c INT, KEY c1(c)) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP INDEX c1;
+Warnings:
+Note	1091	Can't DROP 'fk'; check that column/key exists
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `b` int(11) DEFAULT NULL,
+  `c` int(11) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
diff --git a/mysql-test/t/if_exists.test b/mysql-test/t/if_exists.test
new file mode 100644
index 00000000000..420efaba150
--- /dev/null
+++ b/mysql-test/t/if_exists.test
@@ -0,0 +1,33 @@
+--source include/have_innodb.inc
+
+#
+# MDEV-15308: Assertion `ha_alter_info->alter_info->drop_list.elements > 0' failed in ha_innodb::prepare_inplace_alter_table
+#
+
+CREATE TABLE t1 (a INT, b INT) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP COLUMN b;
+SHOW CREATE TABLE t1;
+ 
+# Cleanup
+DROP TABLE t1;
+
+CREATE TABLE t1 (a INT, b INT) ENGINE=InnoDB;
+ALTER TABLE t1 DROP INDEX IF EXISTS fk, DROP COLUMN b;
+SHOW CREATE TABLE t1;
+ 
+# Cleanup
+DROP TABLE t1;
+
+CREATE TABLE t1 (a INT, b INT, c INT, KEY(c)) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP COLUMN c;
+SHOW CREATE TABLE t1;
+ 
+# Cleanup
+DROP TABLE t1;
+
+CREATE TABLE t1 (a INT, b INT, c INT, KEY c1(c)) ENGINE=InnoDB;
+ALTER TABLE t1 DROP FOREIGN KEY IF EXISTS fk, DROP INDEX c1;
+SHOW CREATE TABLE t1;
+ 
+# Cleanup
+DROP TABLE t1;