conceder select em todos os bancos de dados, exceto um mysql

Execute a saída da seguinte consulta:

SELECT CONCAT("GRANT SELECT ON ",SCHEMA_NAME,".* TO 'test_user'@'localhost';")
FROM information_schema.SCHEMATA 
WHERE SCHEMA_NAME NOT LIKE 'mysql';

Como você tem 200 bancos de dados e não deseja conceder um por um. A maneira mais rápida de fazer isso seria

GRANT SELECT ON *.* TO 'test_user'@'localhost';
FLUSH PRIVILEGES;

E então apenas revogue o privilégio no mysql db

REVOKE SELECT ON mysql.* FROM 'test_user'@'localhost' ;
FLUSH PRIVILEGES;

Mas quando eu GRANT seletivamente e depois REVOKE no mysql.* . Então está funcionando

user@ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 150
Server version: 5.5.41-0ubuntu0.12.04.1 (Ubuntu)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> CREATE USER 'mysqlrockstar'@'localhost';
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW GRANTS FOR 'mysqlrockstar'@'localhost';
+---------------------------------------------------+
| Grants for mysqlrockstar@localhost                |
+---------------------------------------------------+
| GRANT USAGE ON *.* TO 'mysqlrockstar'@'localhost' |
+---------------------------------------------------+
1 row in set (0.00 sec)

mysql> GRANT SELECT ON mysql.* TO 'mysqlrockstar'@'localhost';
Query OK, 0 rows affected (0.00 sec)

mysql> exit;
Bye
user@ubuntu:~$ mysql -u mysqlrockstar
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 151
Server version: 5.5.41-0ubuntu0.12.04.1 (Ubuntu)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
+--------------------+
2 rows in set (0.06 sec)

mysql> exit;
Bye
user@ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 152
Server version: 5.5.41-0ubuntu0.12.04.1 (Ubuntu)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> REVOKE SELECT  ON mysql.* FROM 'mysqlrockstar'@'localhost';
Query OK, 0 rows affected (0.00 sec)

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

mysql> exit;
Bye
user@ubuntu:~$ mysql -u mysqlrockstar
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 153
Server version: 5.5.41-0ubuntu0.12.04.1 (Ubuntu)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)

mysql> use mysql;
ERROR 1044 (42000): Access denied for user 'mysqlrockstar'@'localhost' to database 'mysql'

Anos depois e no MariaDB. O que eu faço:

• conceder acesso a todos os bancos de dados
• conceda apenas 'LOCK TABLES' no mysql.*

O usuário pode ver o mysql, mas nenhuma tabela. Bloquear tabela não funciona, pois o usuário não pode acessar nenhuma tabela.