Question

How can i lock empty rows?

I want to lock an empty select for example:

Session 1

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from users where username = 'nousername' for update;
Empty set (0.01 sec)

mysql>

Session 2

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from users where username = 'nousername' for update;
Empty set (0.00 sec)

mysql>

I need Session 2 to wait until session 1 is completed before the result is returned.

How can i achieve that?

Thanks?

Answer 1

Use an advisory lock.