mysql> grant  select on  *.* to rep@'%' identified by '123';
ERROR 1045 (28000): Access denied for user 'root'@'%' (using password: YES)

mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@%         |
+----------------+
1 row in set (0.00 sec)

mysql> show grants for root@'%' ;

+---------------------------------------------------------------------------------------------------------------------------------------------------------+
|  Grants for root@%                                                                                                                          |
+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY PASSWORD '*228E49B99A5F24B7CDA2CC2A9F4A70635708E6CC' |
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT host,user,password,Grant_priv,Super_priv FROM  mysql.user;

mysql>  SELECT host,user,password,Grant_priv,Super_priv FROM mysql.user;;

mysql> UPDATE mysql.user SET Grant_priv='Y'  WHERE User='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> FLUSH PRIVILEGES;

Query OK, 0 rows affected (0.00 sec)

mysql>  select GRANTEE, PRIVILEGE_TYPE, IS_GRANTABLE from information_schema.user_privileges;

mysql> grant  select on  *.* to rep@'%' identified by '123';
Query OK, 0 rows affected (0.00 sec)