Mysql8建库建表操作记录

一、建库

连接数据库，回车敲入密码

mysql -udev -p

建议指定为utf8mb4，并且排序字符集为utf8mb4_unicode_ci；

CREATE DATABASE IF NOT EXISTS xrw_mmdb DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

执行示例：

mysql> CREATE DATABASE IF NOT EXISTS xrw_mmdb DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Query OK, 1 row affected (0.39 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| xrw_mmdb           |
+--------------------+
5 rows in set (0.00 sec)

mysql>

查看数据库默认设置

mysql> status
--------------
mysql  Ver 8.0.41-0ubuntu0.24.04.1 for Linux on x86_64 ((Ubuntu))

Connection id:          14
Current database:
Current user:           dev@localhost
SSL:                    Not in use
Current pager:          stdout
Using outfile:          ''
Using delimiter:        ;
Server version:         8.0.41-0ubuntu0.24.04.1 (Ubuntu)
Protocol version:       10
Connection:             Localhost via UNIX socket
Server characterset:    utf8mb4
Db     characterset:    utf8mb4
Client characterset:    utf8mb4
Conn.  characterset:    utf8mb4
UNIX socket:            /var/run/mysqld/mysqld.sock
Binary data as:         Hexadecimal
Uptime:                 2 hours 10 min 22 sec

Threads: 5  Questions: 125  Slow queries: 0  Opens: 373  Flush tables: 3  Open tables: 292  Queries per second avg: 0.015
--------------

mysql>

查看所有支持的字符集

mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| binary   | Binary pseudo charset           | binary              |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| utf8mb3  | UTF-8 Unicode                   | utf8mb3_general_ci  |      3 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_0900_ai_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.00 sec)

mysql>

二、建表

use xrw_mmdb
CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(100),
    email VARCHAR(100)
) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

操作示例：

mysql> use xrw_mmdb;
Database changed
mysql> show tables;
Empty set (0.00 sec)

mysql> CREATE TABLE users (
    ->     id INT AUTO_INCREMENT PRIMARY KEY,
    ->     username VARCHAR(100),
    ->     email VARCHAR(100)
    -> ) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Query OK, 0 rows affected (0.24 sec)

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

mysql>

如果已经建好了，就查看一下表字符集

mysql> desc users;
+----------+--------------+------+-----+---------+----------------+
| Field    | Type         | Null | Key | Default | Extra          |
+----------+--------------+------+-----+---------+----------------+
| id       | int          | NO   | PRI | NULL    | auto_increment |
| username | varchar(100) | YES  |     | NULL    |                |
| email    | varchar(100) | YES  |     | NULL    |                |
+----------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

mysql> show create table users \G
*************************** 1. row ***************************
       Table: users
Create Table: CREATE TABLE `users` (
  `id` int NOT NULL AUTO_INCREMENT,
  `username` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `email` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
1 row in set (0.00 sec)

mysql>

三、对比操作

对比一下，如果建库是没有指定字符集和建表时也没有指定字符集，则默认为
CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

mysql> show create table usersa \G
*************************** 1. row ***************************
       Table: usersa
Create Table: CREATE TABLE `usersa` (
  `id` int NOT NULL AUTO_INCREMENT,
  `username` varchar(100) DEFAULT NULL,
  `email` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
1 row in set (0.00 sec)

mysql>

所以，为了统一规范，建议建库时指定好默认的字符集。这样建表时，可以省去不用再指定，若指定也可以，养成好的规范习惯。
规范示例：

CREATE DATABASE IF NOT EXISTS xrw_mmdb DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Create Table: CREATE TABLE `users` (
  `id` int NOT NULL AUTO_INCREMENT,
  `username` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `email` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci