mysql权限问题

mysql> create user 'test1'@'127.0.0.1' identified by '123';
Query OK, 0 rows affected (0.05 sec)

mysql> grant select on . to 'test1'@'127.0.0.1';
Query OK, 0 rows affected (0.01 sec)
mysql> select * from mysql.db where user='test1'\G
Empty set (0.04 sec)
我给test1用户授权所有库，所有的表，为啥mysql.db中没有test1用户呢？？