CREATE TABLE t1(a INT, b INT);
CREATE INDEX IF NOT EXISTS i1 ON t1(a);
SHOW CREATE TABLE t1;
DROP INDEX IF EXISTS i1 ON t1;
SHOW CREATE TABLE t1;
DROP INDEX IF EXISTS i1 ON t1;
SHOW CREATE TABLE t1;

CREATE OR REPLACE INDEX i1 ON t1(a);
SHOW CREATE TABLE t1;
CREATE OR REPLACE INDEX i1 ON t1(a,b);
SHOW CREATE TABLE t1;
DROP TABLE t1;

--error ER_WRONG_USAGE
CREATE OR REPLACE INDEX IF NOT EXISTS i1 ON t1(b,a);