测试read_only的变量的用途。本以为设置为ON以后不可以修改表的内容，创建数据库、表等，结果发现可以建数据库，建表，往表加一条记录.... 无 C:\Documents and Settings\Administratormysql -u rootWelcome to the MySQL monitor. Commands end with ; or \g

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mysql> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only | OFF |
+---------------+-------+
1 row in set (0.02 sec)

mysql> set global read_only=on;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only | ON |
+---------------+-------+
1 row in set (0.00 sec)

mysql> use test
Database changed

mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| y2k |
+----------------+
1 row in set (0.00 sec)

mysql> select * from y2k;
+------------+---------------------+---------------------+
| date | date_time | time_stamp |
+------------+---------------------+---------------------+
| 1998-12-31 | 1998-12-31 23:59:59 | 1998-12-31 23:59:59 |
| 1999-01-01 | 1999-01-01 00:00:00 | 1999-01-01 00:00:00 |
| 1999-09-09 | 1999-09-09 23:59:59 | 1999-09-09 23:59:59 |
| 2000-01-01 | 2000-01-01 00:00:00 | 2000-01-01 00:00:00 |
| 2000-02-28 | 2000-02-28 00:00:00 | 2000-02-28 00:00:00 |
+------------+---------------------+---------------------+
5 rows in set (0.19 sec)

mysql> insert into y2k values ('2000-02-29','2000-02-29 00:00:00',20000229000000
);
Query OK, 1 row affected (0.22 sec)

mysql> select * from y2k;
+------------+---------------------+---------------------+
| date | date_time | time_stamp |
+------------+---------------------+---------------------+
| 1998-12-31 | 1998-12-31 23:59:59 | 1998-12-31 23:59:59 |
| 1999-01-01 | 1999-01-01 00:00:00 | 1999-01-01 00:00:00 |
| 1999-09-09 | 1999-09-09 23:59:59 | 1999-09-09 23:59:59 |
| 2000-01-01 | 2000-01-01 00:00:00 | 2000-01-01 00:00:00 |
| 2000-02-28 | 2000-02-28 00:00:00 | 2000-02-28 00:00:00 |
| 2000-02-29 | 2000-02-29 00:00:00 | 2000-02-29 00:00:00 |
+------------+---------------------+---------------------+
6 rows in set (0.00 sec)

mysql> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only | ON |
+---------------+-------+
1 row in set (0.00 sec)

mysql> create database new;
Query OK, 1 row affected (0.03 sec)

mysql> use new
Database changed

mysql> create table y2k (date DATE, time TIME);
Query OK, 0 rows affected (0.80 sec)

mysql> select database();
+------------+
| database() |
+------------+
| new |
+------------+
1 row in set (0.00 sec)

mysql> insert into new.y2k values ('2013-5-25', '08:53:00');
Query OK, 1 row affected (0.27 sec)

mysql> select * from new.y2k;
+------------+----------+
| date | time |
+------------+----------+
| 2013-05-25 | 08:53:00 |
+------------+----------+
1 row in set (0.00 sec)

mysql>