数据库中关于字符集的操作

一、查看字符集

1.查看MySQL数据库的字符集和校验规则

(1) show variables like 'character%'; (2) show variables like 'collation%'; (3) status; mysql> show variables like 'character%'; +--------------------------+---------------------------------------------------------+ | Variable_name | Value | +--------------------------+---------------------------------------------------------+ | character_set_client | gbk | | character_set_connection | gbk | | character_set_database | utf8 | | character_set_filesystem | binary | | character_set_results | gbk | | character_set_server | utf8 | | character_set_system | utf8 | | character_sets_dir | D:\Program Files\MySQL\MySQL Server 5.7\share\charsets\ | +--------------------------+---------------------------------------------------------+ 8 rows in set, 1 warning (0.01 sec) mysql> show variables like 'collation%'; +----------------------+-----------------+ | Variable_name | Value | +----------------------+-----------------+ | collation_connection | gbk_chinese_ci | | collation_database | utf8_general_ci | | collation_server | utf8_general_ci | +----------------------+-----------------+ 3 rows in set, 1 warning (0.01 sec) mysql> status; -------------- mysql Ver 14.14 Distrib 5.7.24, for Win64 (x86_64) Connection id: 3 Current database: qsurvey Current user: root@localhost SSL: Not in use Using delimiter: ; Server version: 5.7.24-log MySQL Community Server (GPL) Protocol version: 10 Connection: localhost via TCP/IP Server characterset: utf8 Db characterset: utf8 Client characterset: gbk Conn. characterset: gbk TCP port: 3306 Uptime: 2 days 16 hours 49 min 36 sec Threads: 1 Questions: 605 Slow queries: 0 Opens: 147 Flush tables: 1 Open tables: 140 Queries per second avg: 0.002 --------------

character set和collation的区别：

charset=character set（字符集），collation（校验规则），每一个字符集都对应一个校验规则，用于指定数据集是如何排序的，以及字符串的比对规则。

可以使用show collation;来查看所有的校验规则和其对应的字符集。

collation的命名分为这两类：

<charset>_<language/other>_<ci/cs><charset>_bin

例如：utf8_general_ci

ci/cs：大小写是否敏感。ci：case insensitive（大小写不敏感，也就是不区分大小写），cs：case sensitive（大小写敏感，区分大小写）

例如：utf_bin

bin：表示将字符串中的每一个字符用二进制数据存储，并且区分大小写

详细可参考：https://www.cnblogs.com/EasonJim/p/8128196.html

2.查看MYSQL所支持的字符集

show charset; mysql> show charset; +----------+---------------------------------+---------------------+--------+ | Charset | Description | Default collation | Maxlen | +----------+---------------------------------+---------------------+--------+ | big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 | | dec8 | DEC West European | dec8_swedish_ci | 1 | | cp850 | DOS West European | cp850_general_ci | 1 | | hp8 | HP West European | hp8_english_ci | 1 | | koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 | | latin1 | cp1252 West European | latin1_swedish_ci | 1 | | latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 | | swe7 | 7bit Swedish | swe7_swedish_ci | 1 | | ascii | US ASCII | ascii_general_ci | 1 | | ujis | EUC-JP Japanese | ujis_japanese_ci | 3 | | sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 | | hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 | | tis620 | TIS620 Thai | tis620_thai_ci | 1 | | euckr | EUC-KR Korean | euckr_korean_ci | 2 | | koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 | | gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 | | greek | ISO 8859-7 Greek | greek_general_ci | 1 | | cp1250 | Windows Central European | cp1250_general_ci | 1 | | gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 | | latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 | | armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 | | utf8 | UTF-8 Unicode | utf8_general_ci | 3 | | ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 | | cp866 | DOS Russian | cp866_general_ci | 1 | | keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 | | macce | Mac Central European | macce_general_ci | 1 | | macroman | Mac West European | macroman_general_ci | 1 | | cp852 | DOS Central European | cp852_general_ci | 1 | | latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 | | utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci | 4 | | cp1251 | Windows Cyrillic | cp1251_general_ci | 1 | | utf16 | UTF-16 Unicode | utf16_general_ci | 4 | | utf16le | UTF-16LE Unicode | utf16le_general_ci | 4 | | cp1256 | Windows Arabic | cp1256_general_ci | 1 | | cp1257 | Windows Baltic | cp1257_general_ci | 1 | | utf32 | UTF-32 Unicode | utf32_general_ci | 4 | | binary | Binary pseudo charset | binary | 1 | | geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 | | cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 | | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 | | gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 | +----------+---------------------------------+---------------------+--------+ 41 rows in set (0.00 sec)

3.查看库的字符集

（1）show create database 数据库; （2）show create database 数据库\G; mysql> show create database qsurvey; +----------+------------------------------------------------------------------+ | Database | Create Database | +----------+------------------------------------------------------------------+ | qsurvey | CREATE DATABASE `qsurvey` /*!40100 DEFAULT CHARACTER SET utf8 */ | +----------+------------------------------------------------------------------+ 1 row in set (0.00 sec) mysql> show create database qsurvey\G; *************************** 1. row *************************** Database: qsurvey Create Database: CREATE DATABASE `qsurvey` /*!40100 DEFAULT CHARACTER SET utf8 */ 1 row in set (0.00 sec)

4.查看表的字符集

show table status from 库名 like '表名'; mysql> show table status from qsurvey like 'user'; +------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+ | Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment | +------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+ | user | InnoDB | 10 | Dynamic | 9 | 1820 | 16384 | 0 | 0 | 0 | 10 | 2019-05-22 23:16:29 | 2019-05-22 23:20:32 | NULL | utf8_general_ci | NULL | | | +------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+ 1 row in set (0.02 sec) mysql> show table status from qsurvey like 'user'\G; *************************** 1. row *************************** Name: user Engine: InnoDB Version: 10 Row_format: Dynamic Rows: 9 Avg_row_length: 1820 Data_length: 16384 Max_data_length: 0 Index_length: 0 Data_free: 0 Auto_increment: 10 Create_time: 2019-05-22 23:16:29 Update_time: 2019-05-22 23:20:32 Check_time: NULL Collation: utf8_general_ci Checksum: NULL Create_options: Comment: 1 row in set (0.00 sec)

5.查看表中所有列的字符集

show full columns from 表名; mysql> show full columns from user; +-------------+------------------+-----------------+------+-----+-------------------+-----------------------------+---------------------------------+----------------------------+ | Field | Type | Collation | Null | Key | Default | Extra | Privileges | Comment | +-------------+------------------+-----------------+------+-----+-------------------+-----------------------------+---------------------------------+----------------------------+ | id | int(10) unsigned | NULL | NO | PRI | NULL | auto_increment | select,insert,update,references | 自增主键 | | user_name | varchar(20) | utf8_general_ci | NO | | | | select,insert,update,references | 用户名 | | password | varchar(20) | utf8_general_ci | NO | | | | select,insert,update,references | 密码 | | college | varchar(30) | utf8_general_ci | NO | | | | select,insert,update,references | 学院 | | major | varchar(30) | utf8_general_ci | NO | | | | select,insert,update,references | 专业 | | valid | tinyint(4) | NULL | NO | | 1 | | select,insert,update,references | 是否可用：0-不可用，1-可用 | | create_time | timestamp | NULL | NO | | CURRENT_TIMESTAMP | | select,insert,update,references | 创建时间 | | modify_time | timestamp | NULL | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP | select,insert,update,references | 更新时间 | +-------------+------------------+-----------------+------+-----+-------------------+-----------------------------+---------------------------------+----------------------------+ 8 rows in set (0.02 sec)

二、修改字符集

设置字符集一般有两种方法，一种是在创建表的时候设置字符集，另一种是表建成之后修改字符集。

1.创建时指定字符集

创建库的时候指定字符集：

语法：create database 库名 default character set=字符集;

create database qsurvey default character set=utf8;

创建表的时候指定字符集：

语法：create table 表名（属性）default character set = ‘字符集’;

            create table 表名（属性）default charset = 字符集;

//设置存储引擎和字符集 CREATE TABLE `user`( `id` INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT COMMENT '自增主键', `user_name` VARCHAR(20) NOT NULL DEFAULT '' COMMENT '用户名', `password` VARCHAR(20) NOT NULL DEFAULT '' COMMENT '密码', `college` VARCHAR(30) NOT NULL DEFAULT '' COMMENT '学院', `major` VARCHAR(30) NOT NULL DEFAULT '' COMMENT '专业', `valid` TINYINT NOT NULL DEFAULT 1 COMMENT '是否可用：0-不可用，1-可用', `create_time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间', `modify_time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间' )ENGINE=InnoDB DEFAULT CHARSET=utf8; //设置字符集 mysql> create table test(id int,name varchar(10)) default character set = 'gbk'; Query OK, 0 rows affected (0.56 sec) mysql> create table test1(id int,name varchar(10)) default charset = gbk; Query OK, 0 rows affected (0.59 sec)

2.修改字符集

（1）修改全局字符集

/*建立连接使用的编码*/ set character_set_connection=utf8; /*数据库的编码*/ set character_set_database=utf8; /*结果集的编码*/ set character_set_results=utf8; /*数据库服务器的编码*/ set character_set_server=utf8; /*设置数据库系统字符集*/ set character_set_system=utf8; set collation_connection=utf8; set collation_database=utf8; set collation_server=utf8;

（2）修改库的字符集

语法：alter database 库名 default character set 字符集;

alter database tmp default character set gbk;

（3）修改表的字符集

语法：alter table 表名 convert to character set 字符集;

alter table test1 convert to character set utf8;

（4）修改字段的字符集

语法：alter table 表名 modify 字段名 字段属性 character set gbk；

alter table test1 modify name varchar(10) character set gbk;