drop table if exists t1;
CREATE TABLE t1 (a int, unique (a), b int not null, unique(b), c int not null, index(c));
replace into t1 values (1,1,1),(2,2,2),(3,1,3);
select * from t1;
a	b	c
2	2	2
3	1	3
check table t1;
Table	Op	Msg_type	Msg_text
test.t1	check	status	OK
drop table t1;