1CREATE TABLE t1(a INT, b INT); 2CREATE INDEX IF NOT EXISTS i1 ON t1(a); 3SHOW CREATE TABLE t1; 4DROP INDEX IF EXISTS i1 ON t1; 5SHOW CREATE TABLE t1; 6DROP INDEX IF EXISTS i1 ON t1; 7SHOW CREATE TABLE t1; 8 9CREATE OR REPLACE INDEX i1 ON t1(a); 10SHOW CREATE TABLE t1; 11CREATE OR REPLACE INDEX i1 ON t1(a,b); 12SHOW CREATE TABLE t1; 13DROP TABLE t1; 14 15--error ER_WRONG_USAGE 16CREATE OR REPLACE INDEX IF NOT EXISTS i1 ON t1(b,a); 17