• 服务器级别
• 数据库级别
• 表级别
• 列级别

服务器级别

查看:

mysql> SHOW VARIABLES LIKE 'character_set_server';
mysql> SHOW VARIABLES LIKE 'collation_server';

可以使用 SET 修改:

• 修改字符集

mysql> SET character_set_server = gb2312;
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW VARIABLES LIKE 'character_set_server';
+----------------------+--------+
| Variable_name        | Value  |
+----------------------+--------+
| character_set_server | gb2312 |
+----------------------+--------+
1 row in set (0.00 sec)

mysql>  SHOW VARIABLES LIKE 'collation_server';
+------------------+-------------------+
| Variable_name    | Value             |
+------------------+-------------------+
| collation_server | gb2312_chinese_ci |
+------------------+-------------------+
1 row in set (0.00 sec)

• 修改比较规则

mysql> SET collation_server = utf8_general_ci;
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW VARIABLES LIKE 'character_set_server';
+----------------------+-------+
| Variable_name        | Value |
+----------------------+-------+
| character_set_server | utf8  |
+----------------------+-------+
1 row in set (0.00 sec)

mysql> SHOW VARIABLES LIKE 'collation_server';
+------------------+-----------------+
| Variable_name    | Value           |
+------------------+-----------------+
| collation_server | utf8_general_ci |
+------------------+-----------------+
1 row in set (0.00 sec)

数据库级别

在创建或修改时可以指定:

CREATE DATABASE 数据库名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [[DEFAULT] COLLATE 比较规则名称];

ALTER DATABASE 数据库名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [[DEFAULT] COLLATE 比较规则名称];

mysql> CREATE DATABASE charset_demo_db
    -> CHARACTER SET gb2312
    -> COLLATE gb2312_chinese_ci;
Query OK, 1 row affected (0.01 sec)

查看当前数据库级别的设置:

• 需要使用 use 切换到相应的数据库中, 否则显示的值是服务器级别
• 这两个系统变量不能直接修改

mysql> USE charset_demo_db;
Database changed

mysql> SHOW VARIABLES LIKE 'character_set_database';
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| character_set_database | gb2312 |
+------------------------+--------+
1 row in set (0.00 sec)

mysql> SHOW VARIABLES LIKE 'collation_database';
+--------------------+-------------------+
| Variable_name      | Value             |
+--------------------+-------------------+
| collation_database | gb2312_chinese_ci |
+--------------------+-------------------+
1 row in set (0.00 sec)

表级别

• 未指定时, 使用数据库级别的

CREATE TABLE 表名 (列的信息)
    [[DEFAULT] CHARACTER SET 字符集名称]
    [COLLATE 比较规则名称]]

ALTER TABLE 表名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [COLLATE 比较规则名称]

mysql> CREATE TABLE t(
    ->     col VARCHAR(10)
    -> ) CHARACTER SET utf8 COLLATE utf8_general_ci;
Query OK, 0 rows affected (0.03 sec)

列级别

• 未指定时, 使用表级别

CREATE TABLE 表名(
    列名 字符串类型 [CHARACTER SET 字符集名称] [COLLATE 比较规则名称],
    其他列...
);

ALTER TABLE 表名 MODIFY 列名 字符串类型 [CHARACTER SET 字符集名称] [COLLATE 比较规则名称];

mysql> ALTER TABLE t MODIFY col VARCHAR(10) CHARACTER SET gbk COLLATE gbk_chinese_ci;
Query OK, 0 rows affected (0.04 sec)
Records: 0  Duplicates: 0  Warnings: 0