create table t1(n int);
insert into t1 values (1);
lock tables t1 write;
 update low_priority t1 set n = 4;
 select n from t1;
unlock tables;
n
4
drop table t1;
create table t1(n int);
insert into t1 values (1);
lock tables t1 read;
 update low_priority t1 set n = 4;
 select n from t1;
unlock tables;
n
1
drop table t1;