Shulou(Shulou.com)06/01 Report--

As shown in the following example, the execution of a statement when a client connects to MySQL includes the following procedure:

1. Authentication

Whether you can log in to the MySQL server.

two。 Grammar analysis

Judge whether the execution statement is legal, and there are no statement errors.

3. Privilege analysis

Determine whether the statement is executed and whether it has the relevant permissions on the target.

4. Semantic analysis

Determine whether there are corresponding tables and fields

5. Optimized execution

After the optimizer optimizes the SQL statement, it executes and returns the result.

1) mysql-utest-h227.0.0.1-p-P3306-perrorWarning: Using a password on the command line interface can be insecure.ERROR 1045 (28000): Access denied for user 'test'@'127.0.0.1' (using password: YES) mysql > show grants +-- + | Grants for test@127.0.0.1 | +- -+ | GRANT USAGE ON *. * TO 'test'@'127.0.0.1' IDENTIFIED BY PASSWORD | | GRANT SELECT ON `test`.* TO' test'@'127.0.0.1' | | +-+ 2 rows in set (0.00 sec) mysql > mysql > 2) mysql > select * from test.t | ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near'* * from test.t' at line 1mysql > 3) mysql > select * from a.tten error 1142 (42000): SELECT command denied to user 'test'@'127.0.0.1' for table' t'mysql > mysql > 4) mysql > select * from test.t;ERROR 1146 (42S02): Table 'test.t' doesn't existmysql > mysql >

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