文章目录
-
- [1 创建数据库](#1 创建数据库)
-
- [1.1 语法](#1.1 语法)
- [2 创建数据库案例](#2 创建数据库案例)
- [3 字符集和校验规则](#3 字符集和校验规则)
- [4 操纵数据库](#4 操纵数据库)
-
- [4.1 查看数据库](#4.1 查看数据库)
- [4.2 显示创建语句](#4.2 显示创建语句)
- [4.3 修改数据库](#4.3 修改数据库)
- [4.4 数据库删除](#4.4 数据库删除)
- [4.5 备份和恢复](#4.5 备份和恢复)
-
- [4.5.1 备份](#4.5.1 备份)
- [4.5.2 还原](#4.5.2 还原)
- [4.5.3 注意事项](#4.5.3 注意事项)
- [4.6 查看连接情况](#4.6 查看连接情况)
作为后端开发、数据分析师的必备技能，MySQL 数据库的基础操作 ------ 尤其是 "库" 的管理，直接决定了后续数据存储的稳定性和效率。很多新手刚接触时，会卡在 "怎么创建数据库""字符集乱码怎么办""误删数据怎么恢复" 这些问题上。今天这篇文章，就从实战角度出发，把 MySQL 库操作的核心知识点讲透，连细节和避坑点都给你整理好了，看完就能上手！
1 创建数据库
1.1 语法
创建数据库的语法如下：
sql
CREATE DATABASE [IF NOT EXISTS] db_name [create_specification [, create_specification] ...]
create_specification:
[DEFAULT] CHARACTER SET charset_name
[DEFAULT] COLLATE collation_name其中，大写部分为关键字，[]内的内容为可选项；CHARACTER SET用于指定数据库采用的字符集，COLLATE用于指定数据库字符集的校验规则。
2 创建数据库案例
- 创建名为
db1的数据库，语句为create database db1;。当创建数据库未指定字符集和校验规则时，系统默认使用字符集utf8，校验规则为utf8_general_ci。 - 创建使用
utf8字符集的db2数据库，语句为create database db2 charset=utf8;。 - 创建使用
utf8字符集且带校对规则的db3数据库，语句为create database db3 charset=utf8 collate utf8_general_ci;。
这里新建一个test数据库，采用utf8编码：
3 字符集和校验规则
3.1 查看系统默认字符集以及校验规则
查看系统默认字符集的语句为show variables like 'character_set_database';，查看系统默认校验规则的语句为show variables like 'collation_database';。
3.2 查看数据库支持的字符集
查看数据库支持的字符集的语句为show charset;，字符集主要用于控制使用的语言，例如utf8可支持中文。
sql
mysql> show charset;show collation;
+----------+---------------------------------+---------------------+--------+
| 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)3.3 查看数据库支持的字符集校验规则
查看数据库支持的字符集校验规则的语句为show collation;。
sql
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)3.4 校验规则对数据库的影响
不区分大小写
- 创建校验规则使用
utf8_general_ci（不区分大小写）的数据库test1，语句为create database test1 collate utf8_general_ci;； - 之后使用该数据库，语句为
use test1;；创建person表，语句为create table person(name varchar(20));； - 向表中插入数据，语句为
insert into person values('a'); insert into person values('A'); insert into person values('b'); insert into person values('B');。 - 查询时，使用
use test1;切换到test1数据库，执行select * from person where name='a';，会返回name为a和A的两条数据；排序时，执行select * from person order by name;，a和A会归为一组，b和B会归为一组。
sql
mysql> create database test1 charset=utf8 collate=utf8_general_ci;
Query OK, 1 row affected (0.00 sec)
mysql> use test1;
Database changed
mysql> create table person(name varchar(20));
Query OK, 0 rows affected (0.02 sec)
mysql> insert into person values('a'); insert into person values('A'); insert into person values('b'); insert into person values('B');
Query OK, 1 row affected (0.01 sec)
Query OK, 1 row affected (0.00 sec)
Query OK, 1 row affected (0.00 sec)
Query OK, 1 row affected (0.00 sec)
mysql> select * from person where name='a';
+------+
| name |
+------+
| a |
| A |
+------+
2 rows in set (0.00 sec)
mysql> select * from person order by name;
+------+
| name |
+------+
| a |
| A |
| b |
| B |
+------+
4 rows in set (0.00 sec)区分大小写
- 创建校验规则使用
utf8_bin（区分大小写）的数据库test2，语句为create database test2 collate utf8_bin;； - 之后使用该数据库，语句为
use test2;；创建person表，语句为create table person(name varchar(20));；向表中插入与test1数据库相同的数据。 - 查询时，使用
use test2;切换到test2数据库，执行select * from person where name='a';，仅会返回name为a的一条数据；排序时，执行select * from person order by name;，会按照ASCII码顺序排列，结果为A、B、a、b。
sql
mysql> create database test2 charset=utf8 collate=utf8_bin;
Query OK, 1 row affected (0.00 sec)
mysql> use test2;
Database changed
mysql> create table person(name varchar(20));
Query OK, 0 rows affected (0.02 sec)
mysql> insert into person values('a'); insert into person values('A'); insert into person values('b'); insert into person values('B');
Query OK, 1 row affected (0.00 sec)
Query OK, 1 row affected (0.00 sec)
Query OK, 1 row affected (0.00 sec)
Query OK, 1 row affected (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 |
| a |
| b |
+------+
4 rows in set (0.00 sec)4 操纵数据库
4.1 查看数据库
查看数据库的语句为show databases;：
4.2 显示创建语句
显示数据库创建语句的语法为show create database 数据库名;。例如，查看mytest数据库创建语句的示例为：
sql
mysql> show create database mytest;
| Database | Create
| mysql | CREATE DATABASE `mytest` /*!40100 DEFAULT CHARACTER SET utf8 */ |其中，MySQL建议关键字使用大写，但非必须；数据库名字的反引号````````用于防止数据库名与关键字重复；/*!40100 default.... */并非注释，其表示当前MySQL版本大于4.01版本时，执行该语句。
4.3 修改数据库
修改数据库的语法为：
sql
ALTER DATABASE db_name
[alter_spacification [,alter_spacification]...]
alter_spacification:
[DEFAULT] CHARACTER SET charset_name
[DEFAULT] COLLATE collation_name对数据库的修改主要是修改数据库的字符集和校验规则。例如，将mytest数据库字符集改成gbk的语句为mysql> alter database mytest charset=gbk;，执行后查询结果为Query OK, 1 row affected (0.00 sec)，再次查看mytest数据库创建语句，会显示CREATE DATABASE mytest /*!40100 DEFAULT CHARACTER SET gbk */。
4.4 数据库删除
删除数据库的语法为DROP DATABASE [IF EXISTS] db_name;。执行删除操作后，在数据库内部无法看到对应的数据库，且对应的数据库文件夹会被删除，内部数据表也会被级联删除，因此不要随意删除数据库。
4.5 备份和恢复
4.5.1 备份
备份数据库的语法为mysqldump -P 3306 -u root -p -B 'your database name' > '希望保存路径' （注意这不是SQL语句！）。例如，将test库备份到C:\Users\19624\Desktop的语句为 mysqldump -P 3306 -u root -p -B test > C:\Users\19624\Desktop\test.sql，备份文件中包含创建数据库、建表、导入数据的语句。
这里演示将test数据库备份到桌面：
sql
#文件内容如下
-- MySQL dump 10.13 Distrib 5.7.44, for Win64 (x86_64)
--
-- Host: localhost Database: test
-- ------------------------------------------------------
-- Server version 5.7.44-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
--
-- Current Database: `test`
--
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `test` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `test`;
--
-- Table structure for table `person`
--
DROP TABLE IF EXISTS `person`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `person` (
`name` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;
--
-- Dumping data for table `person`
--
LOCK TABLES `person` WRITE;
/*!40000 ALTER TABLE `person` DISABLE KEYS */;
INSERT INTO `person` VALUES ('a'),('A'),('b'),('B');
/*!40000 ALTER TABLE `person` ENABLE KEYS */;
UNLOCK TABLES;
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
-- Dump completed on 2025-10-05 23:57:154.5.2 还原
还原数据库的语句为mysql> source C:\Users\19624\Desktop\test.sql;。
4.5.3 注意事项
- 若备份的是数据库中的某张表，语法为
# mysqldump -u root -p 数据库名 表名1 表名2 > D:/mytest.sql。 - 若同时备份多个数据库，语法为
# mysqldump -u root -p -B 数据库名1 数据库名2 ... > 数据库存放路径。 - 若备份一个数据库时未带上
-B参数，在恢复数据库时，需先创建空数据库，然后使用该数据库，再使用source命令还原。
4.6 查看连接情况
查看数据库连接情况的语法为show processlist。例如：
sql
mysql> show processlist;
+----+------+-----------------+------+---------+------+----------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------------+------+---------+------+----------+------------------+
| 3 | root | localhost:51366 | NULL | Query | 0 | starting | show processlist |
+----+------+-----------------+------+---------+------+----------+------------------+
1 row in set (0.00 sec)该命令可查看当前连接MySQL的用户，若发现非正常登录的用户，可能数据库被入侵；当数据库运行较慢时，也可通过该指令查看连接情况。