From efae1dc8466303dd9c9c69402e5edeb3bd510871 Mon Sep 17 00:00:00 2001 From: jaywcjlove <398188662@qq.com> Date: Sat, 29 Oct 2022 01:33:05 +0800 Subject: [PATCH] doc: add `mysql.md` cheatsheet. --- README.md | 1 + docs/mysql.md | 605 +++++++++++++++++++++++++++++++++++++++ scripts/assets/mysql.svg | 2 + 3 files changed, 608 insertions(+) create mode 100644 docs/mysql.md create mode 100644 scripts/assets/mysql.svg diff --git a/README.md b/README.md index f93806d..74c7731 100644 --- a/README.md +++ b/README.md @@ -24,6 +24,7 @@ Quick Reference [INI](./docs/ini.md) [JSON](./docs/json.md) [Markdown](./docs/markdown.md) +[MySQL](./docs/mysql.md) [Swift](./docs/swift.md) [SwiftUI](./docs/swiftui.md) [TOML](./docs/toml.md) diff --git a/docs/mysql.md b/docs/mysql.md new file mode 100644 index 0000000..0031686 --- /dev/null +++ b/docs/mysql.md @@ -0,0 +1,605 @@ +MySQL 备忘清单 +=== + +本备忘单旨在快速理解 [MySQL](https://mysql.com) 所涉及的主要概念，提供了最常用的SQL语句，供您参考。 + + +入门 +--- + +### 介绍 + + +MySQL 为关系型数据库(Relational Database Management System)，一个关系型数据库由一个或数个表格组成，如下所示的一个表格 + +---- + +```bash + name ▼ 键 ▼ 列(col) +┌┈┈┈┈┬┈┈┈┈┈┈┈┈┬┈┈┈┈┈┈┬┈┈┈┈┈┈┈┐ +┆ id ┆ name ┆ uid ┆ level ┆ ◀ 表头header +├┈┈┈┈┼┈┈┈┈┈┈┈┈┤┈┈┈┈┈┈┤┈┈┈┈┈┈┈┤ +┆ 1 ┆ mysql ┆ 0 ┆ 3 ┆ +├┈┈┈┈┼┈┈┈┈┈┈┈┈┤┈┈┈┈┈┈┤┈┈┈┈┈┈┈┤ +┆ 2 ┆ redis ┆ 12 ┆ 1 ┆ ◀ 行 row +└┈┈┈┈┴┈┈┈┈┈┈┈┈┴┈┈┈┈┈┈┴┈┈┈┈┈┈┈┘ + redis ▲ 值 +``` + +---- + +- `表头(header)` 每一列的名称 +- `列(col)` 具有相同数据类型的数据的集合 +- `行(row)` 每一行用来描述某个人/物的具体信息 +- `值(value)` 行的具体信息，每个值与该列数据类型相同 +- `键(key)` 用来识别某个特定的人/物的方法，有唯一性 + +### 登录MySQL + +```shell +# 默认用户名，-p 是密码， +# ⚠️参数后面不需要空格 +mysql -h 127.0.0.1 -u <用户名> -p<密码> +mysql -D 数据库名 -h 主机名 -u 用户名 -p +mysql -h -P <端口号> -u -p [db_name] +mysql -h -u -p [db_name] +``` + +### 常用的 + + +#### 数据库 Database + +:-|:- +:-|:- +`CREATE DATABASE` db `;` | `创建`数据库 +`SHOW DATABASES;` | `列出`数据库 +`USE` db`;` | `切换`到数据库 +`CONNECT` db `;` | `切换`到数据库 +`DROP DATABASE` db`;` | `删除`数据库 + +#### 表 Table + +:-|:- +:-|:- +`SHOW TABLES;` | 列出当前数据库的表 +`SHOW FIELDS FROM` t`;` | 表的列表字段 +`DESC` t`;` | 显示表格结构 +`SHOW CREATE TABLE `t`;` | 显示创建表sql +`TRUNCATE TABLE `t`;` | 删除表中的所有数据 +`DROP TABLE `t`;` | 删除表格 + +#### Proccess + +:-|:- +:-|:- +`show processlist;` | 列出进程 +`kill` pid`;` | 杀死进程 + +### 查看 MySQL 信息 + +```shell +# 显示当前mysql的version的各种信息 +mysql> status; +# 显示当前mysql的version信息 +mysql> select version(); +# 查看 MySQL 端口号 +mysql> show global variables like 'port'; +``` + +### 退出MySQL会话 + +```bash +mysql> exit +``` + +退出 `quit;` 或 `\q;` 一样的效果 + +### 备份 + +创建备份 + +```sql +mysqldump -u user -p db_name > db.sql +``` + +导出不带架构的数据库 + +```shell +mysqldump -u user -p db_name --no-data=true --add-drop-table=false > db.sql +``` + + +恢复备份 + +```shell +mysql -u user -p db_name < db.sql +``` + +MySQL 示例 +------ + +### 管理表格 + +创建一个包含三列的新表 + +```sql +CREATE TABLE t ( + id INT, + name VARCHAR DEFAULT NOT NULL, + price INT DEFAULT 0 + PRIMARY KEY(id) +); +``` + +从数据库中删除表 + +```sql +DROP TABLE t ; +``` + +向表中添加新列 + +```sql +ALTER TABLE t ADD column; +``` + +从表中删除列c + +```sql +ALTER TABLE t DROP COLUMN c ; +``` + +添加约束 + +```sql +ALTER TABLE t ADD constraint; +``` + +删除约束 + +```sql +ALTER TABLE t DROP constraint; +``` + +将表从t1重命名为t2 + +```sql +ALTER TABLE t1 RENAME TO t2; +``` + +将列c1重命名为c2 + +```sql +ALTER TABLE t1 RENAME c1 TO c2 ; +``` + +删除表中的所有数据 + +```sql +TRUNCATE TABLE t; +``` + +### 从表中查询数据 + +从表中查询列c1、c2中的数据 + +```sql +SELECT c1, c2 FROM t +``` + +查询表中的所有行和列 + +```sql +SELECT * FROM t +``` + +查询数据并使用条件筛选行 + +```sql +SELECT c1, c2 FROM t +WHERE condition +``` + +查询表中的不同行 + +```sql +SELECT DISTINCT c1 FROM t +WHERE condition +``` + +按升序或降序对结果集排序 + +```sql +SELECT c1, c2 FROM t +ORDER BY c1 ASC [DESC] +``` + +跳过行的偏移并返回下n行 + +```sql +SELECT c1, c2 FROM t +ORDER BY c1 +LIMIT n OFFSET offset +``` + +使用聚合函数对行进行分组 + +```sql +SELECT c1, aggregate(c2) +FROM t +GROUP BY c1 +``` + +使用HAVING子句筛选组 + +```sql +SELECT c1, aggregate(c2) +FROM t +GROUP BY c1 +HAVING condition +``` + +### 从多个表查询 + + +内部连接 t1 和 t2 + +```sql +SELECT c1, c2 +FROM t1 +INNER JOIN t2 ON condition +``` + +左连接t1和t1 + +```sql +SELECT c1, c2 +FROM t1 +LEFT JOIN t2 ON condition +``` + +右连接t1和t2 + +```sql +SELECT c1, c2 +FROM t1 +RIGHT JOIN t2 ON condition +``` + +执行完全外部连接 + +```sql +SELECT c1, c2 +FROM t1 +FULL OUTER JOIN t2 ON condition +``` + +生成表中行的笛卡尔积 + +```sql +SELECT c1, c2 +FROM t1 +CROSS JOIN t2 +``` + +执行交叉连接的另一种方法 + +```sql +SELECT c1, c2 +FROM t1, t2 +``` + +使用INNER Join子句将t1连接到自身 + +```sql +SELECT c1, c2 +FROM t1 A +INNER JOIN t1 B ON condition +``` + +使用SQL运算符，合并两个查询中的行 + +```sql +SELECT c1, c2 FROM t1 +UNION [ALL] +SELECT c1, c2 FROM t2 +``` + +返回两个查询的交集 + +```sql +SELECT c1, c2 FROM t1 +INTERSECT +SELECT c1, c2 FROM t2 +``` + +从另一个结果集中减去一个结果集 + +```sql +SELECT c1, c2 FROM t1 +MINUS +SELECT c1, c2 FROM t2 +``` + +使用模式匹配%查询行_ + +```sql +SELECT c1, c2 FROM t1 +WHERE c1 [NOT] LIKE pattern +``` + +查询列表中的行 + +```sql +SELECT c1, c2 FROM t +WHERE c1 [NOT] IN value_list +``` + +查询两个值之间的行 + +```sql +SELECT c1, c2 FROM t +WHERE c1 BETWEEN low AND high +``` + +检查表中的值是否为NULL + +```sql +SELECT c1, c2 FROM t +WHERE c1 IS [NOT] NULL +``` + +### 使用 SQL 约束 + +将c1和c2设置为主键 + +```sql +CREATE TABLE t( + c1 INT, c2 INT, c3 VARCHAR, + PRIMARY KEY (c1,c2) +); +``` + +将c2列设置为外键 + +```sql +CREATE TABLE t1( + c1 INT PRIMARY KEY, + c2 INT, + FOREIGN KEY (c2) REFERENCES t2(c2) +); +``` + +使c1和c2中的值唯一 + +```sql +CREATE TABLE t( + c1 INT, c1 INT, + UNIQUE(c2,c3) +); +``` + +确保c1>0和c1>=c2中的值 + +```sql +CREATE TABLE t( + c1 INT, c2 INT, + CHECK(c1> 0 AND c1 >= c2) +); +``` +c2列中的设置值不为NULL + +```sql +CREATE TABLE t( + c1 INT PRIMARY KEY, + c2 VARCHAR NOT NULL +); +``` + +### 修改数据 + +在表格中插入一行 + +```sql +INSERT INTO t(column_list) +VALUES(value_list); +``` + +在表格中插入多行 + +```sql +INSERT INTO t(column_list) +VALUES (value_list), + (value_list), …; +``` + +将行从t2插入t1 + +```sql +INSERT INTO t1(column_list) +SELECT column_list +FROM t2; +``` + +更新列c1中所有行的新值 + +```sql +UPDATE t +SET c1 = new_value; +``` + +更新列c1、c2中与条件匹配的值 + +```sql +UPDATE t +SET c1 = new_value, + c2 = new_value +WHERE condition; +``` + +删除表中的所有数据 + +```sql +DELETE FROM t; +``` + +删除表中的行子集 + +```sql +DELETE FROM t +WHERE condition; +``` + +### 管理视图 + + +创建由c1和c2组成的新视图 + +```sql +CREATE VIEW v(c1,c2) +AS +SELECT c1, c2 +FROM t; +``` + +使用选中选项创建新视图 + +```sql +CREATE VIEW v(c1,c2) +AS +SELECT c1, c2 +FROM t; +WITH [CASCADED | LOCAL] CHECK OPTION; +``` + +创建递归视图 + +```sql +CREATE RECURSIVE VIEW v +AS +select-statement -- anchor part +UNION [ALL] +select-statement; -- recursive part +``` + +创建临时视图 + +```sql +CREATE TEMPORARY VIEW v +AS +SELECT c1, c2 +FROM t; +``` + +删除视图 + +```sql +DROP VIEW view_name; +``` + +### 管理触发器 + +创建或修改触发器 + +```sql +CREATE OR MODIFY TRIGGER trigger_name +WHEN EVENT +ON table_name TRIGGER_TYPE +EXECUTE stored_procedure; +``` + +#### WHEN + +:-|:- +:-|:- +`BEFORE` | 在事件发生前调用 +`AFTER` | 事件发生后调用 + +#### EVENT + +:-|:- +:-|:- +`INSERT` | 为INSERT调用 +`UPDATE` | 调用UPDATE +`DELETE` | 调用DELETE + +#### TRIGGER_TYPE + +:-|:- +:-|:- +`FOR EACH ROW` | - +`FOR EACH STATEMENT` | - + +### 管理索引 + +在t表的c1和c2上创建索引 + +```sql +CREATE INDEX idx_name +ON t(c1,c2); +``` + +在t表的c3、c4上创建唯一索引 + +```sql +CREATE UNIQUE INDEX idx_name +ON t(c3,c4) +``` + +删除索引 + +```sql +DROP INDEX idx_name; +``` + +MySQL 数据类型 +--------- + + +### Strings + +| - | - | +|--------------|-----------------------------| +| `CHAR` | String (0 - 255) | +| `VARCHAR` | String (0 - 255) | +| `TINYTEXT` | String (0 - 255) | +| `TEXT` | String (0 - 65535) | +| `BLOB` | String (0 - 65535) | +| `MEDIUMTEXT` | String (0 - 16777215) | +| `MEDIUMBLOB` | String (0 - 16777215) | +| `LONGTEXT` | String (0 - 429496­7295) | +| `LONGBLOB` | String (0 - 429496­7295) | +| `ENUM` | One of preset options | +| `SET` | Selection of preset options | + + +### Date & time +| Data Type | Format | +|-------------|---------------------| +| `DATE ` | yyyy-MM-dd | +| `TIME ` | hh:mm:ss | +| `DATETIME ` | yyyy-MM-dd hh:mm:ss | +| `TIMESTAMP` | yyyy-MM-dd hh:mm:ss | +| `YEAR ` | yyyy | + + +### Numeric + +| - | - | +|---------------|---------------------------------------------------------------| +| `TINYINT x` | Integer (-128 to 127) | +| `SMALLINT x` | Integer (-32768 to 32767) | +| `MEDIUMINT x` | Integer (-8388608 to 8388607) | +| `INT x` | Integer (-2147­483648 to 214748­3647) | +| `BIGINT x` | Integer (-9223­372­036­854­775808 to 922337­203­685­477­5807) | +| `FLOAT` | Decimal (precise to 23 digits) | +| `DOUBLE` | Decimal (24 to 53 digits) | +| `DECIMAL` | "­DOU­BLE­" stored as string | + +另见 +--- + +- [SQL 基础教程](http://www.w3school.com.cn/sql/index.asp) _(w3school.com.cn)_ +- [SQL 语句教程](http://www.1keydata.com/cn/sql/sql-count.php) _(1keydata.com)_ +- [21分钟 MySQL 基础入门](https://jaywcjlove.github.io/mysql-tutorial/21-minutes-MySQL-basic-entry.html) _(jaywcjlove.github.io)_ \ No newline at end of file diff --git a/scripts/assets/mysql.svg b/scripts/assets/mysql.svg new file mode 100644 index 0000000..aa2ea62 --- /dev/null +++ b/scripts/assets/mysql.svg @@ -0,0 +1,2 @@ + + \ No newline at end of file