文章目录
-
- [2. 库的操作](#2. 库的操作)
-
- [2.1 创建数据库](#2.1 创建数据库)
- [2.2 创建数据库案例](#2.2 创建数据库案例)
- [2.3 字符集和校验规则](#2.3 字符集和校验规则)
-
- [2.3.1 查看系统默认字符集以及校验规则](#2.3.1 查看系统默认字符集以及校验规则)
- [2.3.2 查看数据库支持的字符集](#2.3.2 查看数据库支持的字符集)
- [2.3.3 查看数据库支持的字符集校验规则](#2.3.3 查看数据库支持的字符集校验规则)
- [2.3.4 校验规则对数据库的影响](#2.3.4 校验规则对数据库的影响)
- [2.4 操纵数据库](#2.4 操纵数据库)
-
- [2.4.1 查看数据库](#2.4.1 查看数据库)
- [2.4.2 显示创建语句](#2.4.2 显示创建语句)
- [2.4.3 修改数据库](#2.4.3 修改数据库)
- [2.4.4 数据库删除](#2.4.4 数据库删除)
- [2.4.5 备份和恢复 -- 放在最后](#2.4.5 备份和恢复 -- 放在最后)
-
- [2.4.5.1 备份](#2.4.5.1 备份)
- [2.4.5.2 还原](#2.4.5.2 还原)
- [2.4.5.3 注意事项](#2.4.5.3 注意事项)
- [2.4.6 查看连接情况](#2.4.6 查看连接情况)
2. 库的操作
2.1 创建数据库
语法：
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CREATE DATABASE [IF NOT EXISTS] db_name [create_specification [,
create_specification] ...]
create_specification:
[DEFAULT] CHARACTER SET charset_name
[DEFAULT] COLLATE collation_name说明：
- 大写的表示关键字
- \[\] 是可选项
- CHARACTER SET: 指定数据库采用的字符集
- COLLATE: 指定数据库字符集的校验规则
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[root@VM-4-3-centos MySQL]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 5.7.44 MySQL Community Server (GPL)
Copyright (c) 2000, 2023, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> create database database1;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| database1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
6 rows in set (0.00 sec)
mysql> drop database database1;
Query OK, 0 rows affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| helloworld |
| mysql |
| performance_schema |
| sys |
| youcanseeme |
+--------------------+
6 rows in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> create database if not exists database1;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| database1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
6 rows in set (0.00 sec)
mysql> create database if not exists database1;
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| database1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
+--------------------+
6 rows in set (0.00 sec)
mysql> drop database database1;
Query OK, 0 rows affected (0.00 sec)
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[root@VM-4-3-centos MySQL]# cd /var/lib/mysql
[root@VM-4-3-centos mysql]# ll
total 122948
-rw-r----- 1 mysql mysql 56 Jul 3 00:17 auto.cnf
-rw------- 1 mysql mysql 1676 Jul 3 00:17 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 client-cert.pem
-rw------- 1 mysql mysql 1676 Jul 3 00:17 client-key.pem
drwxr-x--- 2 mysql mysql 4096 Jul 3 20:23 helloworld
-rw-r----- 1 mysql mysql 288 Jul 3 00:38 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 3 20:30 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 3 20:30 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 3 00:17 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 3 00:38 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 mysql
srwxrwxrwx 1 mysql mysql 0 Jul 3 00:38 mysql.sock
-rw------- 1 mysql mysql 5 Jul 3 00:38 mysql.sock.lock
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 performance_schema
-rw------- 1 mysql mysql 1680 Jul 3 00:17 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Jul 3 00:17 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 server-cert.pem
-rw------- 1 mysql mysql 1680 Jul 3 00:17 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Jul 3 00:17 sys
[root@VM-4-3-centos mysql]# ll
total 122952
-rw-r----- 1 mysql mysql 56 Jul 3 00:17 auto.cnf
-rw------- 1 mysql mysql 1676 Jul 3 00:17 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 client-cert.pem
-rw------- 1 mysql mysql 1676 Jul 3 00:17 client-key.pem
drwxr-x--- 2 mysql mysql 4096 Jul 4 16:20 database1
drwxr-x--- 2 mysql mysql 4096 Jul 3 20:23 helloworld
-rw-r----- 1 mysql mysql 288 Jul 3 00:38 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 3 20:30 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 3 20:30 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 3 00:17 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 3 00:38 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 mysql
srwxrwxrwx 1 mysql mysql 0 Jul 3 00:38 mysql.sock
-rw------- 1 mysql mysql 5 Jul 3 00:38 mysql.sock.lock
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 performance_schema
-rw------- 1 mysql mysql 1680 Jul 3 00:17 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Jul 3 00:17 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 server-cert.pem
-rw------- 1 mysql mysql 1680 Jul 3 00:17 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Jul 3 00:17 sys
[root@VM-4-3-centos mysql]# ll
total 122948
-rw-r----- 1 mysql mysql 56 Jul 3 00:17 auto.cnf
-rw------- 1 mysql mysql 1676 Jul 3 00:17 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 client-cert.pem
-rw------- 1 mysql mysql 1676 Jul 3 00:17 client-key.pem
drwxr-x--- 2 mysql mysql 4096 Jul 3 20:23 helloworld
-rw-r----- 1 mysql mysql 288 Jul 3 00:38 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 3 20:30 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 3 20:30 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 3 00:17 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 3 00:38 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 mysql
srwxrwxrwx 1 mysql mysql 0 Jul 3 00:38 mysql.sock
-rw------- 1 mysql mysql 5 Jul 3 00:38 mysql.sock.lock
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 performance_schema
-rw------- 1 mysql mysql 1680 Jul 3 00:17 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Jul 3 00:17 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 server-cert.pem
-rw------- 1 mysql mysql 1680 Jul 3 00:17 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Jul 3 00:17 sys
[root@VM-4-3-centos mysql]# mkdir youcanseeme
[root@VM-4-3-centos mysql]# rm -rf youcanseeme2.2 创建数据库案例
- 创建名为 db1 的数据库
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create database db1;说明：当我们创建数据库没有指定字符集和校验规则时，系统使用默认字符集：utf8，校验规则是：utf8_ general_ ci
- 创建一个使用utf8字符集的 db2 数据库
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create database db2 charset=utf8;- 创建一个使用utf字符集，并带校对规则的 db3 数据库
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create database db3 charset=utf8 collate utf8_general_ci;
2.3 字符集和校验规则
2.3.1 查看系统默认字符集以及校验规则
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show variables like 'character_set_database';
show variables like 'collation_database';2.3.2 查看数据库支持的字符集
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show charset;字符集主要是控制用什么语言。比如utf8就可以使用中文。
2.3.3 查看数据库支持的字符集校验规则
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show collation;
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mysql> show variables like 'character_set_database';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| character_set_database | utf8 |
+------------------------+-------+
1 row in set (0.00 sec)
mysql> show variables like 'collation_database';
+--------------------+-----------------+
| Variable_name | Value |
+--------------------+-----------------+
| collation_database | utf8_general_ci |
+--------------------+-----------------+
1 row in set (0.00 sec)
mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name | Value |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database | utf8_general_ci |
| collation_server | utf8_general_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)
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)
mysql> show collation;
+--------------------------+----------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------------+----------+-----+---------+----------+---------+
| big5_chinese_ci | big5 | 1 | Yes | Yes | 1 |
| big5_bin | big5 | 84 | | Yes | 1 |
| dec8_swedish_ci | dec8 | 3 | Yes | Yes | 1 |
| dec8_bin | dec8 | 69 | | Yes | 1 |
| cp850_general_ci | cp850 | 4 | Yes | Yes | 1 |
| cp850_bin | cp850 | 80 | | Yes | 1 |
| hp8_english_ci | hp8 | 6 | Yes | Yes | 1 |
| hp8_bin | hp8 | 72 | | Yes | 1 |
| koi8r_general_ci | koi8r | 7 | Yes | Yes | 1 |
| koi8r_bin | koi8r | 74 | | Yes | 1 |
| latin1_german1_ci | latin1 | 5 | | Yes | 1 |
| latin1_swedish_ci | latin1 | 8 | Yes | Yes | 1 |
| latin1_danish_ci | latin1 | 15 | | Yes | 1 |
| latin1_german2_ci | latin1 | 31 | | Yes | 2 |
| latin1_bin | latin1 | 47 | | Yes | 1 |
| latin1_general_ci | latin1 | 48 | | Yes | 1 |
| latin1_general_cs | latin1 | 49 | | Yes | 1 |
| latin1_spanish_ci | latin1 | 94 | | Yes | 1 |
| latin2_czech_cs | latin2 | 2 | | Yes | 4 |
| latin2_general_ci | latin2 | 9 | Yes | Yes | 1 |
| latin2_hungarian_ci | latin2 | 21 | | Yes | 1 |
| latin2_croatian_ci | latin2 | 27 | | Yes | 1 |
| latin2_bin | latin2 | 77 | | Yes | 1 |
| swe7_swedish_ci | swe7 | 10 | Yes | Yes | 1 |
| swe7_bin | swe7 | 82 | | Yes | 1 |
| ascii_general_ci | ascii | 11 | Yes | Yes | 1 |
| ascii_bin | ascii | 65 | | Yes | 1 |
| ujis_japanese_ci | ujis | 12 | Yes | Yes | 1 |
| ujis_bin | ujis | 91 | | Yes | 1 |
| sjis_japanese_ci | sjis | 13 | Yes | Yes | 1 |
| sjis_bin | sjis | 88 | | Yes | 1 |
| hebrew_general_ci | hebrew | 16 | Yes | Yes | 1 |
| hebrew_bin | hebrew | 71 | | Yes | 1 |
| tis620_thai_ci | tis620 | 18 | Yes | Yes | 4 |
| tis620_bin | tis620 | 89 | | Yes | 1 |
| euckr_korean_ci | euckr | 19 | Yes | Yes | 1 |
| euckr_bin | euckr | 85 | | Yes | 1 |
| koi8u_general_ci | koi8u | 22 | Yes | Yes | 1 |
| koi8u_bin | koi8u | 75 | | Yes | 1 |
| gb2312_chinese_ci | gb2312 | 24 | Yes | Yes | 1 |
| gb2312_bin | gb2312 | 86 | | Yes | 1 |
| greek_general_ci | greek | 25 | Yes | Yes | 1 |
| greek_bin | greek | 70 | | Yes | 1 |
| cp1250_general_ci | cp1250 | 26 | Yes | Yes | 1 |
| cp1250_czech_cs | cp1250 | 34 | | Yes | 2 |
| cp1250_croatian_ci | cp1250 | 44 | | Yes | 1 |
| cp1250_bin | cp1250 | 66 | | Yes | 1 |
| cp1250_polish_ci | cp1250 | 99 | | Yes | 1 |
| gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 |
| gbk_bin | gbk | 87 | | Yes | 1 |
| latin5_turkish_ci | latin5 | 30 | Yes | Yes | 1 |
| latin5_bin | latin5 | 78 | | Yes | 1 |
| armscii8_general_ci | armscii8 | 32 | Yes | Yes | 1 |
| armscii8_bin | armscii8 | 64 | | Yes | 1 |
| utf8_general_ci | utf8 | 33 | Yes | Yes | 1 |
| utf8_bin | utf8 | 83 | | Yes | 1 |
| utf8_unicode_ci | utf8 | 192 | | Yes | 8 |
| utf8_icelandic_ci | utf8 | 193 | | Yes | 8 |
| utf8_latvian_ci | utf8 | 194 | | Yes | 8 |
| utf8_romanian_ci | utf8 | 195 | | Yes | 8 |
| utf8_slovenian_ci | utf8 | 196 | | Yes | 8 |
| utf8_polish_ci | utf8 | 197 | | Yes | 8 |
| utf8_estonian_ci | utf8 | 198 | | Yes | 8 |
| utf8_spanish_ci | utf8 | 199 | | Yes | 8 |
| utf8_swedish_ci | utf8 | 200 | | Yes | 8 |
| utf8_turkish_ci | utf8 | 201 | | Yes | 8 |
| utf8_czech_ci | utf8 | 202 | | Yes | 8 |
| utf8_danish_ci | utf8 | 203 | | Yes | 8 |
| utf8_lithuanian_ci | utf8 | 204 | | Yes | 8 |
| utf8_slovak_ci | utf8 | 205 | | Yes | 8 |
| utf8_spanish2_ci | utf8 | 206 | | Yes | 8 |
| utf8_roman_ci | utf8 | 207 | | Yes | 8 |
| utf8_persian_ci | utf8 | 208 | | Yes | 8 |
| utf8_esperanto_ci | utf8 | 209 | | Yes | 8 |
| utf8_hungarian_ci | utf8 | 210 | | Yes | 8 |
| utf8_sinhala_ci | utf8 | 211 | | Yes | 8 |
| utf8_german2_ci | utf8 | 212 | | Yes | 8 |
| utf8_croatian_ci | utf8 | 213 | | Yes | 8 |
| utf8_unicode_520_ci | utf8 | 214 | | Yes | 8 |
| utf8_vietnamese_ci | utf8 | 215 | | Yes | 8 |
| utf8_general_mysql500_ci | utf8 | 223 | | Yes | 1 |
| ucs2_general_ci | ucs2 | 35 | Yes | Yes | 1 |
| ucs2_bin | ucs2 | 90 | | Yes | 1 |
| ucs2_unicode_ci | ucs2 | 128 | | Yes | 8 |
| ucs2_icelandic_ci | ucs2 | 129 | | Yes | 8 |
| ucs2_latvian_ci | ucs2 | 130 | | Yes | 8 |
| ucs2_romanian_ci | ucs2 | 131 | | Yes | 8 |
| ucs2_slovenian_ci | ucs2 | 132 | | Yes | 8 |
| ucs2_polish_ci | ucs2 | 133 | | Yes | 8 |
| ucs2_estonian_ci | ucs2 | 134 | | Yes | 8 |
| ucs2_spanish_ci | ucs2 | 135 | | Yes | 8 |
| ucs2_swedish_ci | ucs2 | 136 | | Yes | 8 |
| ucs2_turkish_ci | ucs2 | 137 | | Yes | 8 |
| ucs2_czech_ci | ucs2 | 138 | | Yes | 8 |
| ucs2_danish_ci | ucs2 | 139 | | Yes | 8 |
| ucs2_lithuanian_ci | ucs2 | 140 | | Yes | 8 |
| ucs2_slovak_ci | ucs2 | 141 | | Yes | 8 |
| ucs2_spanish2_ci | ucs2 | 142 | | Yes | 8 |
| ucs2_roman_ci | ucs2 | 143 | | Yes | 8 |
| ucs2_persian_ci | ucs2 | 144 | | Yes | 8 |
| ucs2_esperanto_ci | ucs2 | 145 | | Yes | 8 |
| ucs2_hungarian_ci | ucs2 | 146 | | Yes | 8 |
| ucs2_sinhala_ci | ucs2 | 147 | | Yes | 8 |
| ucs2_german2_ci | ucs2 | 148 | | Yes | 8 |
| ucs2_croatian_ci | ucs2 | 149 | | Yes | 8 |
| ucs2_unicode_520_ci | ucs2 | 150 | | Yes | 8 |
| ucs2_vietnamese_ci | ucs2 | 151 | | Yes | 8 |
| ucs2_general_mysql500_ci | ucs2 | 159 | | Yes | 1 |
| cp866_general_ci | cp866 | 36 | Yes | Yes | 1 |
| cp866_bin | cp866 | 68 | | Yes | 1 |
| keybcs2_general_ci | keybcs2 | 37 | Yes | Yes | 1 |
| keybcs2_bin | keybcs2 | 73 | | Yes | 1 |
| macce_general_ci | macce | 38 | Yes | Yes | 1 |
| macce_bin | macce | 43 | | Yes | 1 |
| macroman_general_ci | macroman | 39 | Yes | Yes | 1 |
| macroman_bin | macroman | 53 | | Yes | 1 |
| cp852_general_ci | cp852 | 40 | Yes | Yes | 1 |
| cp852_bin | cp852 | 81 | | Yes | 1 |
| latin7_estonian_cs | latin7 | 20 | | Yes | 1 |
| latin7_general_ci | latin7 | 41 | Yes | Yes | 1 |
| latin7_general_cs | latin7 | 42 | | Yes | 1 |
| latin7_bin | latin7 | 79 | | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 |
| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 8 |
| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 8 |
| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 8 |
| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 8 |
| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 8 |
| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 8 |
| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 8 |
| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 8 |
| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 8 |
| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 8 |
| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 8 |
| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 8 |
| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 8 |
| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 8 |
| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 8 |
| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 8 |
| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 8 |
| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 8 |
| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 8 |
| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 8 |
| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 8 |
| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 8 |
| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 8 |
| cp1251_bulgarian_ci | cp1251 | 14 | | Yes | 1 |
| cp1251_ukrainian_ci | cp1251 | 23 | | Yes | 1 |
| cp1251_bin | cp1251 | 50 | | Yes | 1 |
| cp1251_general_ci | cp1251 | 51 | Yes | Yes | 1 |
| cp1251_general_cs | cp1251 | 52 | | Yes | 1 |
| utf16_general_ci | utf16 | 54 | Yes | Yes | 1 |
| utf16_bin | utf16 | 55 | | Yes | 1 |
| utf16_unicode_ci | utf16 | 101 | | Yes | 8 |
| utf16_icelandic_ci | utf16 | 102 | | Yes | 8 |
| utf16_latvian_ci | utf16 | 103 | | Yes | 8 |
| utf16_romanian_ci | utf16 | 104 | | Yes | 8 |
| utf16_slovenian_ci | utf16 | 105 | | Yes | 8 |
| utf16_polish_ci | utf16 | 106 | | Yes | 8 |
| utf16_estonian_ci | utf16 | 107 | | Yes | 8 |
| utf16_spanish_ci | utf16 | 108 | | Yes | 8 |
| utf16_swedish_ci | utf16 | 109 | | Yes | 8 |
| utf16_turkish_ci | utf16 | 110 | | Yes | 8 |
| utf16_czech_ci | utf16 | 111 | | Yes | 8 |
| utf16_danish_ci | utf16 | 112 | | Yes | 8 |
| utf16_lithuanian_ci | utf16 | 113 | | Yes | 8 |
| utf16_slovak_ci | utf16 | 114 | | Yes | 8 |
| utf16_spanish2_ci | utf16 | 115 | | Yes | 8 |
| utf16_roman_ci | utf16 | 116 | | Yes | 8 |
| utf16_persian_ci | utf16 | 117 | | Yes | 8 |
| utf16_esperanto_ci | utf16 | 118 | | Yes | 8 |
| utf16_hungarian_ci | utf16 | 119 | | Yes | 8 |
| utf16_sinhala_ci | utf16 | 120 | | Yes | 8 |
| utf16_german2_ci | utf16 | 121 | | Yes | 8 |
| utf16_croatian_ci | utf16 | 122 | | Yes | 8 |
| utf16_unicode_520_ci | utf16 | 123 | | Yes | 8 |
| utf16_vietnamese_ci | utf16 | 124 | | Yes | 8 |
| utf16le_general_ci | utf16le | 56 | Yes | Yes | 1 |
| utf16le_bin | utf16le | 62 | | Yes | 1 |
| cp1256_general_ci | cp1256 | 57 | Yes | Yes | 1 |
| cp1256_bin | cp1256 | 67 | | Yes | 1 |
| cp1257_lithuanian_ci | cp1257 | 29 | | Yes | 1 |
| cp1257_bin | cp1257 | 58 | | Yes | 1 |
| cp1257_general_ci | cp1257 | 59 | Yes | Yes | 1 |
| utf32_general_ci | utf32 | 60 | Yes | Yes | 1 |
| utf32_bin | utf32 | 61 | | Yes | 1 |
| utf32_unicode_ci | utf32 | 160 | | Yes | 8 |
| utf32_icelandic_ci | utf32 | 161 | | Yes | 8 |
| utf32_latvian_ci | utf32 | 162 | | Yes | 8 |
| utf32_romanian_ci | utf32 | 163 | | Yes | 8 |
| utf32_slovenian_ci | utf32 | 164 | | Yes | 8 |
| utf32_polish_ci | utf32 | 165 | | Yes | 8 |
| utf32_estonian_ci | utf32 | 166 | | Yes | 8 |
| utf32_spanish_ci | utf32 | 167 | | Yes | 8 |
| utf32_swedish_ci | utf32 | 168 | | Yes | 8 |
| utf32_turkish_ci | utf32 | 169 | | Yes | 8 |
| utf32_czech_ci | utf32 | 170 | | Yes | 8 |
| utf32_danish_ci | utf32 | 171 | | Yes | 8 |
| utf32_lithuanian_ci | utf32 | 172 | | Yes | 8 |
| utf32_slovak_ci | utf32 | 173 | | Yes | 8 |
| utf32_spanish2_ci | utf32 | 174 | | Yes | 8 |
| utf32_roman_ci | utf32 | 175 | | Yes | 8 |
| utf32_persian_ci | utf32 | 176 | | Yes | 8 |
| utf32_esperanto_ci | utf32 | 177 | | Yes | 8 |
| utf32_hungarian_ci | utf32 | 178 | | Yes | 8 |
| utf32_sinhala_ci | utf32 | 179 | | Yes | 8 |
| utf32_german2_ci | utf32 | 180 | | Yes | 8 |
| utf32_croatian_ci | utf32 | 181 | | Yes | 8 |
| utf32_unicode_520_ci | utf32 | 182 | | Yes | 8 |
| utf32_vietnamese_ci | utf32 | 183 | | Yes | 8 |
| binary | binary | 63 | Yes | Yes | 1 |
| geostd8_general_ci | geostd8 | 92 | Yes | Yes | 1 |
| geostd8_bin | geostd8 | 93 | | Yes | 1 |
| cp932_japanese_ci | cp932 | 95 | Yes | Yes | 1 |
| cp932_bin | cp932 | 96 | | Yes | 1 |
| eucjpms_japanese_ci | eucjpms | 97 | Yes | Yes | 1 |
| eucjpms_bin | eucjpms | 98 | | Yes | 1 |
| gb18030_chinese_ci | gb18030 | 248 | Yes | Yes | 2 |
| gb18030_bin | gb18030 | 249 | | Yes | 1 |
| gb18030_unicode_520_ci | gb18030 | 250 | | Yes | 8 |
+--------------------------+----------+-----+---------+----------+---------+
222 rows in set (0.00 sec)
mysql> create database d1;
Query OK, 1 row affected (0.00 sec)
mysql> create database d2 charset=utf8;
Query OK, 1 row affected (0.00 sec)
mysql> create database d3 character set utf8;
Query OK, 1 row affected (0.01 sec)
mysql> create database d4 charset=utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)
mysql> create database d5 charset=gbk collate gbk_chinese_ci;
Query OK, 1 row affected (0.00 sec)
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[root@VM-4-3-centos mysql]# ll
total 122952
-rw-r----- 1 mysql mysql 56 Jul 3 00:17 auto.cnf
-rw------- 1 mysql mysql 1676 Jul 3 00:17 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 client-cert.pem
-rw------- 1 mysql mysql 1676 Jul 3 00:17 client-key.pem
drwxr-x--- 2 mysql mysql 4096 Jul 4 16:49 d1
drwxr-x--- 2 mysql mysql 4096 Jul 3 20:23 helloworld
-rw-r----- 1 mysql mysql 288 Jul 3 00:38 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 3 20:30 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 3 20:30 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 3 00:17 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 3 00:38 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 mysql
srwxrwxrwx 1 mysql mysql 0 Jul 3 00:38 mysql.sock
-rw------- 1 mysql mysql 5 Jul 3 00:38 mysql.sock.lock
drwxr-x--- 2 mysql mysql 4096 Jul 3 00:17 performance_schema
-rw------- 1 mysql mysql 1680 Jul 3 00:17 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Jul 3 00:17 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Jul 3 00:17 server-cert.pem
-rw------- 1 mysql mysql 1680 Jul 3 00:17 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Jul 3 00:17 sys
[root@VM-4-3-centos mysql]# ls d1
db.opt
[root@VM-4-3-centos mysql]# cat d1/db.opt
default-character-set=utf8
default-collation=utf8_general_ci
[root@VM-4-3-centos mysql]# ls d2
db.opt
[root@VM-4-3-centos mysql]# cat d2/db.opt
default-character-set=utf8
default-collation=utf8_general_ci
[root@VM-4-3-centos mysql]# ls d3
db.opt
[root@VM-4-3-centos mysql]# cat d3/db.opt
default-character-set=utf8
default-collation=utf8_general_ci
[root@VM-4-3-centos mysql]# cat d4/db.opt
default-character-set=utf8
default-collation=utf8_general_ci
[root@VM-4-3-centos mysql]# cat d5/db.opt
default-character-set=gbk
default-collation=gbk_chinese_ci
[root@VM-4-3-centos mysql]# vim /etc/my.cnf2.3.4 校验规则对数据库的影响
- 不区分大小写
创建一个数据库，校验规则使用utf8_ general_ ci不区分大小写
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create database test1 collate utf8_general_ci;
use test1;
create table person(name varchar(20));
insert into person values('a');
insert into person values('A');
insert into person values('b');
insert into person values('B');- 区分大小写
创建一个数据库，校验规则使用utf8_ bin区分大小写
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create database test2 collate utf8_bin;
use test2
create table person(name varchar(20));
insert into person values('a');
insert into person values('A');
insert into person values('b');
insert into person values('B');- 进行查询
不区分大小写的查询以及结果
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mysql> use test1;
mysql> select * from person where name='a';
+------+
| name |
+------+
| a |
| A |
+------+
2 rows in set (0.01 sec)- 区分大小写的查询以及结果
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mysql> use test2;
mysql> select * from person where name='a';
+------+
| name |
+------+
| a |
+------+
2 rows in set (0.01 sec)- 结果排序
不区分大小写排序以及结果：
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mysql> use test1;
mysql> select * from person order by name;
+------+
| name |
+------+
| a |
| A |
| b |
| B |
+------+- 区分大小写排序以及结果：
c
mysql> use test2;
mysql> select * from person order by name;
+------+
| name |
+------+
| A |
| B |
| a |
| b |
+------+
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mysql> create database test1 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)
mysql> create database test2 collate utf8_bin;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| d2 |
| d3 |
| d4 |
| d5 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test1 |
| test2 |
+--------------------+
12 rows in set (0.00 sec)
mysql> use test1;
Database changed
mysql> create table if not exists person(name varchar(20));
Query OK, 0 rows affected (0.03 sec)
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| person |
+-----------------+
1 row in set (0.00 sec)
mysql> desc person;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
1 row in set (0.00 sec)
mysql> insert into person (name) values ('a');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('b');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('A');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('B');
Query OK, 1 row affected (0.01 sec)
mysql> insert into person (name) values ('c');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('D');
Query OK, 1 row affected (0.00 sec)
mysql> select * from person;
+------+
| name |
+------+
| a |
| b |
| A |
| B |
| c |
| D |
+------+
6 rows in set (0.00 sec)
mysql> select * from person where name='a';
+------+
| name |
+------+
| a |
| A |
+------+
2 rows in set (0.00 sec)
mysql> use test2;
Database changed
mysql> create table if not exists person (name varchar(20));
Query OK, 0 rows affected (0.02 sec)
mysql> show tables;
+-----------------+
| Tables_in_test2 |
+-----------------+
| person |
+-----------------+
1 row in set (0.00 sec)
mysql> insert into person (name) values ('a');
Query OK, 1 row affected (0.01 sec)
mysql> insert into person (name) values ('A');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('b');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('B');
Query OK, 1 row affected (0.01 sec)
mysql> insert into person (name) values ('c');
Query OK, 1 row affected (0.00 sec)
mysql> insert into person (name) values ('C');
Query OK, 1 row affected (0.00 sec)
mysql> select * from person;
+------+
| name |
+------+
| a |
| A |
| b |
| B |
| c |
| C |
+------+
6 rows in set (0.00 sec)
mysql> select * from person where name='a';
+------+
| name |
+------+
| a |
+------+
1 row in set (0.00 sec)
mysql> select * from person order by name;
+------+
| name |
+------+
| A |
| B |
| C |
| a |
| b |
| c |
+------+
6 rows in set (0.00 sec)
mysql> use test1;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from person order by name;
+------+
| name |
+------+
| a |
| A |
| b |
| B |
| c |
| D |
+------+
6 rows in set (0.00 sec)
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[root@VM-4-3-centos mysql]# cat test1/db.opt
default-character-set=utf8
default-collation=utf8_general_ci
[root@VM-4-3-centos mysql]# cat test2/db.opt
default-character-set=utf8
default-collation=utf8_bin
[root@VM-4-3-centos mysql]# ls test1/
db.opt person.frm person.ibd
[root@VM-4-3-centos mysql]# ls test2/
db.opt person.frm person.ibd2.4 操纵数据库
2.4.1 查看数据库
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show databases;2.4.2 显示创建语句
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show create database 数据库名；示例：
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mysql> show create database mytest;
+----------+----------------------------------------------------------------+
| Database | Create Database |
+----------+----------------------------------------------------------------+
| mysql | CREATE DATABASE `mytest` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+----------------------------------------------------------------+说明：
- MySQL 建议我们关键字使用大写，但是不是必须的。
- 数据库名字的反引号``,是为了防止使用的数据库名刚好是关键字
- /*!40100 default... */ 这个不是注释，表示当前mysql版本大于4.01版本，就执行这句话
2.4.3 修改数据库
语法：
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ALTER DATABASE db_name
[alter_spacification [,alter_spacification]...]
alter_spacification:
[DEFAULT] CHARACTER SET charset_name
[DEFAULT] COLLATE collation_name说明：
- 对数据库的修改主要指的是修改数据库的字符集，校验规则
实例： 将 mytest 数据库字符集改成 gbk
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mysql> alter database mytest charset=gbk;
Query OK, 1 row affected (0.00 sec)
mysql> show create database mytest;
+----------+----------------------------------------------------------------+
| Database | Create Database |
+----------+----------------------------------------------------------------+
| mytest | CREATE DATABASE `mytest` /*!40100 DEFAULT CHARACTER SET gbk */ |
+----------+----------------------------------------------------------------+2.4.4 数据库删除
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DROP DATABASE [IF EXISTS] db_ name;执行删除之后的结果:
- 数据库内部看不到对应的数据库
- 对应的数据库文件夹被删除，级联删除，里面的数据表全部被删
注意：不要随意删除数据库
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mysql> drop database d5;
Query OK, 0 rows affected (0.01 sec)
mysql> drop database d4;
Query OK, 0 rows affected (0.00 sec)
mysql> drop database d3;
Query OK, 0 rows affected (0.00 sec)
mysql> drop database d2;
Query OK, 0 rows affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test1 |
| test2 |
+--------------------+
8 rows in set (0.00 sec)
mysql> use d1;
Database changed
mysql> show tables;
Empty set (0.00 sec)
mysql> select database();
+------------+
| database() |
+------------+
| d1 |
+------------+
1 row in set (0.00 sec)
mysql> use test2;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select database();
+------------+
| database() |
+------------+
| test2 |
+------------+
1 row in set (0.00 sec)
mysql> alter database test2 charset=gbk collate gbk_chinese_ci;
Query OK, 1 row affected (0.00 sec)
mysql> show create database test2;
+----------+---------------------------------------------------------------+
| Database | Create Database |
+----------+---------------------------------------------------------------+
| test2 | CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET gbk */ |
+----------+---------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> alter database test2 charset=utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)
mysql> show create database test2;
+----------+----------------------------------------------------------------+
| Database | Create Database |
+----------+----------------------------------------------------------------+
| test2 | CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+----------------------------------------------------------------+
1 row in set (0.00 sec)
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[root@VM-4-3-centos mysql]# cat test2/db.opt
default-character-set=utf8
default-collation=utf8_bin
[root@VM-4-3-centos mysql]# cat test2/db.opt
default-character-set=gbk
default-collation=gbk_chinese_ci
[root@VM-4-3-centos mysql]# cat test2/db.opt
default-character-set=utf8
default-collation=utf8_general_ci2.4.5 备份和恢复 -- 放在最后
2.4.5.1 备份
语法：
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# mysqldump -P3306 -u root -p 密码 -B 数据库名 > 数据库备份存储的文件路径示例：将mytest库备份到文件（退出连接）
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# mysqldump -P3306 -u root -p123456 -B mytest > D:/mytest.sql这时，可以打开看看 mytest.sql 文件里的内容，其实把我们整个创建数据库，建表，导入数据的语句都装载这个文件中。
2.4.5.2 还原
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mysql> source D:/mysql-5.7.22/mytest.sql;2.4.5.3 注意事项
- 如果备份的不是整个数据库，而是其中的一张表，怎么做？
c
# mysqldump -u root -p 数据库名 表名1 表名2 > D:/mytest.sql- 同时备份多个数据库
c
# mysqldump -u root -p -B 数据库名1 数据库名2 ... > 数据库存放路径- 如果备份一个数据库时，没有带上-B参数， 在恢复数据库时，需要先创建空数据库，然后使用数据库，再使用source来还原。
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[root@VM-4-3-centos mysql]# cd ~/MySQL/
[root@VM-4-3-centos MySQL]# ll
total 0
[root@VM-4-3-centos MySQL]# mysqldump -P3306 -uroot -p -B test1 > test1.sql
Enter password:
[root@VM-4-3-centos MySQL]# ll
total 4
-rw-r--r-- 1 root root 1968 Jul 5 14:58 test1.sql
[root@VM-4-3-centos MySQL]# vim test1.sql
[root@VM-4-3-centos MySQL]# ls /var/lib/mysql
auto.cnf client-key.pem ibdata1 mysql private_key.pem sys
ca-key.pem d1 ib_logfile0 mysql.sock public_key.pem test2
ca.pem helloworld ib_logfile1 mysql.sock.lock server-cert.pem
client-cert.pem ib_buffer_pool ibtmp1 performance_schema server-key.pem
[root@VM-4-3-centos MySQL]# pwd
/root/MySQL
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mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test1 |
| test2 |
+--------------------+
8 rows in set (0.00 sec)
mysql> use test1;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| person |
+-----------------+
1 row in set (0.00 sec)
mysql> select * from person;
+------+
| name |
+------+
| a |
| b |
| A |
| B |
| c |
| D |
+------+
6 rows in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test1 |
| test2 |
+--------------------+
8 rows in set (0.00 sec)
mysql> drop database test1;
Query OK, 1 row affected (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test2 |
+--------------------+
7 rows in set (0.00 sec)
mysql> source /root/MySQL/test1.sql;
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected, 1 warning (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 1 row affected (0.00 sec)
Database changed
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.02 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 6 rows affected (0.00 sec)
Records: 6 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected, 1 warning (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| d1 |
| helloworld |
| mysql |
| performance_schema |
| sys |
| test1 |
| test2 |
+--------------------+
8 rows in set (0.00 sec)
mysql> use test1;
Database changed
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| person |
+-----------------+
1 row in set (0.00 sec)
mysql> select * from person;
+------+
| name |
+------+
| a |
| b |
| A |
| B |
| c |
| D |
+------+
6 rows in set (0.00 sec)2.4.6 查看连接情况
语法：
c
show processlist;示例：
c
mysql> show processlist;
+----+------+-----------+------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+------+---------+------+-------+------------------+
| 2 | root | localhost | test | Sleep | 1386 | | NULL |
| 3 | root | localhost | NULL | Query | 0 | NULL | show processlist |
+----+------+-----------+------+---------+------+-------+------------------+可以告诉我们当前有哪些用户连接到我们的MySQL，如果查出某个用户不是你正常登陆的，很有可能你的数据库被人入侵了。以后大家发现自己数据库比较慢时，可以用这个指令来查看数据库连接情况。
c
mysql> show processlist;
+----+------+-----------+-------+---------+------+----------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+-------+---------+------+----------+------------------+
| 10 | root | localhost | test1 | Query | 0 | starting | show processlist |
+----+------+-----------+-------+---------+------+----------+------------------+
1 row in set (0.00 sec)