From cd26f7528ae1146029cf686b06c7d5b62f8d66f4 Mon Sep 17 00:00:00 2001
From: expressgy <x71291@outlook.com>
Date: Sun, 24 Mar 2024 01:34:30 +0800
Subject: [PATCH] =?UTF-8?q?=E5=AD=A6=E4=B9=A0mysql?=
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---
 docs/MySQL/mysql是怎样使用的.md         | 50 +++++++++++++++++++
 ...ql是怎样使用的数据初始化7.0.sql | 48 ++++++++++++++++++
 2 files changed, 98 insertions(+)
 create mode 100644 docs/MySQL/mysql是怎样使用的数据初始化7.0.sql

diff --git a/docs/MySQL/mysql是怎样使用的.md b/docs/MySQL/mysql是怎样使用的.md
index a7f4f0b..8eb102b 100644
--- a/docs/MySQL/mysql是怎样使用的.md
+++ b/docs/MySQL/mysql是怎样使用的.md
@@ -400,11 +400,61 @@ CREATE TABLE zerofille_table (
 
 # 第七章 简单查询
 
+## 7.1 准备
 
+采用`mysql是怎样使用的数据初始化7.0.sql`导入数据
 
+## 7.2 查询单个列
 
+- 方法：`SELECT 列名 FROM 表名`
 
+### 7.2.1 列的别名
 
+- 方法：`SELECT 列名 [AS] 列的别名 FROM 表名`
+
+```sql
+SELECT number AS '学号' FROM student_info;
+SELECT number '学号' FROM student_info;
+```
+
+## 7.3 查询多个列
+
+- 方法：`SELECT 列1,列2,列3,列4,列5 FROM 表名;`
+
+```sql
+SELECT 
+    number, name, id_number, major 
+FROM 
+    student_info;
+SELECT 
+    number '学号', name '姓名', id_number '身份证号', major '专业' 
+FROM 
+    student_info;
+```
+
+### 7.4 查询所有列
+
+- 方法：`SELECT * FROM student_info;`
+
+### 7.5 查询结果去重
+
+- 方法：`SELECT DISTINCT department[, 列名] FROM student_info`
+
+```sql
+SELECT DISTINCT department FROM student_info;
+SELECT DISTINCT department, major FROM student_info;
+```
+
+### 7.6 限制结果集合记录条数（分页）
+
+- 方法：`SELECT * FROM table_name LIMIT [起始下标, ]搜寻条数`
+
+```sql
+# 查询前两条
+SELECT * FROM student_info LIMIT 2;
+# 查询两条，从5+1开始
+SELECT * FROM student_info LIMIT 5, 2;
+```
 
 
 
diff --git a/docs/MySQL/mysql是怎样使用的数据初始化7.0.sql b/docs/MySQL/mysql是怎样使用的数据初始化7.0.sql
new file mode 100644
index 0000000..a415e8d
--- /dev/null
+++ b/docs/MySQL/mysql是怎样使用的数据初始化7.0.sql
@@ -0,0 +1,48 @@
+USE hutao;
+
+CREATE TABLE IF NOT EXISTS
+    student_info
+(
+    number INT PRIMARY KEY COMMENT '学生ID信息表的主键',
+    name VARCHAR(5) NOT NULL COMMENT '学生姓名',
+    sex ENUM('男', '女') COMMENT '学生性别',
+    id_number CHAR(18) COMMENT '身份证',
+    department VARCHAR(30) COMMENT '学院',
+    major VARCHAR(30) COMMENT '专业',
+    enrollment_time DATE COMMENT '入学时间',
+    UNIQUE KEY id_number (id_number)
+) COMMENT '学生信息表';
+
+CREATE TABLE IF NOT EXISTS
+    student_score
+(
+    number INT COMMENT '学生ID',
+    subject VARCHAR(30) COMMENT '学科',
+    score INT NOT NULL COMMENT '成绩',
+    PRIMARY KEY (number, subject),
+    CONSTRAINT FOREIGN KEY (number) REFERENCES student_info(number)
+) COMMENT '学生成绩表';
+
+SHOW CREATE TABLE student_info;
+
+INSERT INTO
+    student_info(number, name, sex, id_number, department, major, enrollment_time)
+VALUES
+    (20210101, '狗哥', '男', '158177200301044792', '计算机学院', '计算机科学与工程', '2021-09-01'),
+    (20210102, '猫爷', '男', '151008200201178529', '计算机学院', '计算机科学与工程', '2021-09-01'),
+    (20210103, '艾希', '女', '17156320010116959X', '计算机学院', '软件工程', '2021-09-01'),
+    (20210104, '亚索', '男', '141992200201078600', '计算机学院', '计算机科学与工程', '2021-09-01'),
+    (20210105, '莫甘娜', '女', '181048200008156368', '航天学院', '飞行器设计', '2021-09-01'),
+    (20210106, '赵信', '男', '197995200201078445', '航天学院', '电子信息', '2021-09-01');
+
+INSERT INTO
+    student_score(number, subject, score)
+VALUES
+    (20210101, '计算机是怎样运行的', 78),
+    (20210101, 'MySQL是怎样运行的', 88),
+    (20210102, '计算机是怎样运行的', 100),
+    (20210102, 'MySQL是怎样运行的', 98),
+    (20210103, '计算机是怎样运行的', 59),
+    (20210103, 'MySQL是怎样运行的', 61),
+    (20210104, '计算机是怎样运行的', 55),
+    (20210104, 'MySQL是怎样运行的', 46);