drop table if exists t1;
create table t1 (a int not null auto_increment,b int, primary key (a)) type=myisam auto_increment=3;
insert into t1 values (1,1),(NULL,3),(NULL,4);
delete from t1 where a=4;
insert into t1 values (NULL,5),(NULL,6);
select * from t1;
a	b
1	1
3	3
5	5
6	6
delete from t1 where a=6;
replace t1 values (3,1);
ALTER TABLE t1 add c int;
replace t1 values (3,3,3);
insert into t1 values (NULL,7,7);
update t1 set a=8,b=b+1,c=c+1 where a=7;
insert into t1 values (NULL,9,9);
select * from t1;
a	b	c
1	1	NULL
3	3	3
5	5	NULL
8	8	8
9	9	9
drop table t1;
create table t1 (
skey tinyint unsigned NOT NULL auto_increment PRIMARY KEY,
sval char(20)
);
insert into t1 values (NULL, "hello");
insert into t1 values (NULL, "hey");
select * from t1;
skey	sval
1	hello
2	hey
select _rowid,t1._rowid,skey,sval from t1;
_rowid	_rowid	skey	sval
1	1	1	hello
2	2	2	hey
drop table t1;
create table t1 (a char(10) not null, b int not null auto_increment, primary key(a,b));
insert into t1 values ("a",1),("b",2),("a",2),("c",1);
insert into t1 values ("a",NULL),("b",NULL),("c",NULL),("e",NULL);
insert into t1 (a) values ("a"),("b"),("c"),("d");
insert into t1 (a) values ('k'),('d');
insert into t1 (a) values ("a");
insert into t1 values ("d",last_insert_id());
select * from t1;
a	b
a	1
a	2
a	3
a	4
a	5
b	2
b	3
b	4
c	1
c	2
c	3
d	1
d	2
d	5
e	1
k	1
drop table t1;
create table t1 (ordid int(8) not null auto_increment, ord  varchar(50) not null, primary key (ordid), index(ord,ordid));
insert into t1 (ordid,ord) values (NULL,'sdj'),(NULL,'sdj');
select * from t1;
ordid	ord
1	sdj
2	sdj
drop table t1;
create table t1 (ordid int(8) not null auto_increment, ord  varchar(50) not null, primary key (ord,ordid));
insert into t1 values (NULL,'sdj'),(NULL,'sdj'),(NULL,"abc"),(NULL,'abc'),(NULL,'zzz'),(NULL,'sdj'),(NULL,'abc');
select * from t1;
ordid	ord
1	abc
2	abc
3	abc
1	sdj
2	sdj
3	sdj
1	zzz
drop table t1;
create table t1 (a int not null primary key auto_increment);
insert into t1 values (0);
update t1 set a=0;
select * from t1;
a
0
check table t1;
Table	Op	Msg_type	Msg_text
test.t1	check	warning	Found row where the auto_increment column has the value 0
test.t1	check	status	OK
drop table t1;