set session transaction isolation level read committed;
create table t1(a int not null) engine=innodb DEFAULT CHARSET=latin1;
insert into t1 values (1),(2),(3),(4),(5),(6),(7);
set autocommit=0;
select * from t1 where a=3 lock in share mode;
a
3
set session transaction isolation level read committed;
set autocommit=0;
update t1 set a=10 where a=5;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
commit;
update t1 set a=10 where a=5;
select * from t1 where a=2 for update;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
select * from t1 where a=2 limit 1 for update;
a
2
update t1 set a=11 where a=6;
update t1 set a=12 where a=2;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
update t1 set a=13 where a=1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
commit;
update t1 set a=14 where a=1;
commit;
select * from t1;
a
14
2
3
4
10
11
7
drop table t1;