create temporary table t1 (col1 int not null, col2 char(4) not null, primary key(col1)) engine=memory;
alter table t1 engine=myisam;
insert into t1 values (1,1),(5,2),(2,3),(3,4),(4,4);
select * from t1;
update t1 set col2='7' where col1='4';
select * from t1;
DROP TABLE t1;