一、查看字符集
1.查看MySQL數據庫的字符集和校驗規則
(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的區別：
charset=character set（字符集），collation（校驗規則），每一個字符集都對應一個校驗規則，用於指定數據集是如何排序的，以及字符串的比對規則。
可以使用show collation;來查看所有的校驗規則和其對應的字符集。
collation的命名分爲這兩類：
- <charset>_<language/other>_<ci/cs>
- <charset>_bin
例如：utf8_general_ci
ci/cs：大小寫是否敏感。ci：case insensitive（大小寫不敏感，也就是不區分大小寫），cs：case sensitive（大小寫敏感，區分大小寫）
例如：utf_bin
bin：表示將字符串中的每一個字符用二進制數據存儲，並且區分大小寫
詳細可參考：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.查看庫的字符集
（1）show create database 數據庫;
（2）show create database 數據庫\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.查看錶的字符集
show table status from 庫名 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.查看錶中所有列的字符集
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 | 自增主鍵 |
| user_name | varchar(20) | utf8_general_ci | NO | | | | select,insert,update,references | 用戶名 |
| password | varchar(20) | utf8_general_ci | NO | | | | select,insert,update,references | 密碼 |
| college | varchar(30) | utf8_general_ci | NO | | | | select,insert,update,references | 學院 |
| major | varchar(30) | utf8_general_ci | NO | | | | select,insert,update,references | 專業 |
| 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 | 創建時間 |
| modify_time | timestamp | NULL | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP | select,insert,update,references | 更新時間 |
+-------------+------------------+-----------------+------+-----+-------------------+-----------------------------+---------------------------------+----------------------------+
8 rows in set (0.02 sec)
二、修改字符集
設置字符集一般有兩種方法，一種是在創建表的時候設置字符集，另一種是表建成之後修改字符集。
1.創建時指定字符集
創建庫的時候指定字符集：
語法：create database 庫名 default character set=字符集;
create database qsurvey default character set=utf8;
創建表的時候指定字符集：
語法：create table 表名（屬性）default character set = ‘字符集’;
create table 表名（屬性）default charset = 字符集;
//設置存儲引擎和字符集
CREATE TABLE `user`(
`id` INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT COMMENT '自增主鍵',
`user_name` VARCHAR(20) NOT NULL DEFAULT '' COMMENT '用戶名',
`password` VARCHAR(20) NOT NULL DEFAULT '' COMMENT '密碼',
`college` VARCHAR(30) NOT NULL DEFAULT '' COMMENT '學院',
`major` VARCHAR(30) NOT NULL DEFAULT '' COMMENT '專業',
`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 '創建時間',
`modify_time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新時間'
)ENGINE=InnoDB DEFAULT CHARSET=utf8;
//設置字符集
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
/*建立連接使用的編碼*/
set character_set_connection=utf8;
/*數據庫的編碼*/
set character_set_database=utf8;
/*結果集的編碼*/
set character_set_results=utf8;
/*數據庫服務器的編碼*/
set character_set_server=utf8;
/*設置數據庫系統字符集*/
set character_set_system=utf8;
set collation_connection=utf8;
set collation_database=utf8;
set collation_server=utf8;
（2）修改庫的字符集
語法：alter database 庫名 default character set 字符集;
alter database tmp default character set gbk;
（3）修改表的字符集
語法：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
語法：alter table 表名 modify 字段名 字段屬性 character set gbk；
alter table test1 modify name varchar(10) character set gbk;