diff --git a/blog/php-mysql/index.md b/blog/php-mysql/index.md
index ce9d1509e27c2f5d8e66f8231ff12d4fc7b8cafb..e32b42dacd2841e23ca1623ecbbb112d76e8c547 100644
--- a/blog/php-mysql/index.md
+++ b/blog/php-mysql/index.md
@@ -49,3 +49,7 @@
 [数据库备份与还原](blog/php-mysql/sql-bak.md)
 
 [用户权限管理](blog/php-mysql/sql-power.md)
+
+[外键 foreing key](blog/php-mysql/sql-foreing-key.md)
+
+[视图 view](blog/php-mysql/sql-view.md)
diff --git a/blog/php-mysql/sql-foreing-key.md b/blog/php-mysql/sql-foreing-key.md
new file mode 100644
index 0000000000000000000000000000000000000000..37b04ecb620260c89cf5988db78c53fa00986a69
--- /dev/null
+++ b/blog/php-mysql/sql-foreing-key.md
@@ -0,0 +1,318 @@
+# 外键 foreing key
+
+外键表示了两个实体之间的联系
+
+外键 foreing key: A表中的一个字段的值指向另B表的主键
+
+- B: 主表
+- A: 从表
+
+```
+主表：主键（主关键字） = 从表：外键（外关键字）
+```
+
+## 1、外键操作
+### 1.1、增加外键
+
+
+基本语法
+
+方式一：创建表的时候增加外键
+```sql
+[constraint `外键名`] foreign key (外键字段) references 主表(主键);
+```
+方式二：创建表后增加外键
+```sql
+alter table 从表 add [constraint `外关键字`] foreign key (外键字段) references 主表(主键);
+```
+
+示例1： 创建表的时候增加外键
+
+```sql
+-- 创建外键
+create table my_foreign(
+    id int primary key auto_increment,
+    name varchar(10) not null,
+    class_id int,
+    -- 创建时，会自动增加普通索引
+    foreign key (class_id) references my_class(id)
+);
+
+mysql> show create table my_foreign;
+CREATE TABLE `my_foreign` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci NOT NULL,
+  `class_id` int(11) DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `class_id` (`class_id`),
+  CONSTRAINT `my_foreign_ibfk_1` FOREIGN KEY (`class_id`) REFERENCES `my_class` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+
+mysql> desc my_foreign;
++----------+-------------+------+-----+---------+----------------+
+| Field    | Type        | Null | Key | Default | Extra          |
++----------+-------------+------+-----+---------+----------------+
+| id       | int(11)     | NO   | PRI | NULL    | auto_increment |
+| name     | varchar(10) | NO   |     | NULL    |                |
+| class_id | int(11)     | YES  | MUL | NULL    |                |
++----------+-------------+------+-----+---------+----------------+
+3 rows in set (0.01 sec)
+
+```
+MUL多索引 外键本身也是索引
+
+示例2： 创建表后增加外键
+```sql
+-- 查看原来的表
+mysql> desc my_class;
++-------+-------------+------+-----+---------+----------------+
+| Field | Type        | Null | Key | Default | Extra          |
++-------+-------------+------+-----+---------+----------------+
+| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
+| name  | varchar(10) | NO   | UNI | NULL    |                |
++-------+-------------+------+-----+---------+----------------+
+2 rows in set (0.01 sec)
+
+mysql> show create table my_class;
+CREATE TABLE `my_class` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci NOT NULL,
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `name` (`name`)
+) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+
+mysql> desc my_student;
++----------+-------------+------+-----+---------+----------------+
+| Field    | Type        | Null | Key | Default | Extra          |
++----------+-------------+------+-----+---------+----------------+
+| id       | int(11)     | NO   | PRI | NULL    | auto_increment |
+| name     | varchar(10) | YES  |     | NULL    |                |
+| class_id | int(11)     | YES  |     | NULL    |                |
+| age      | int(11)     | YES  |     | NULL    |                |
+| gender   | int(11)     | YES  |     | NULL    |                |
++----------+-------------+------+-----+---------+----------------+
+
+mysql> show create table my_student\G
+*************************** 1. row ***************************
+       Table: my_student
+Create Table: CREATE TABLE `my_student` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci DEFAULT NULL,
+  `class_id` int(11) DEFAULT NULL,
+  `age` int(11) DEFAULT NULL,
+  `gender` int(11) DEFAULT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+-- 增加外键
+alter table my_student add constraint fk_class_id foreign key (class_id) references my_class(id);
+
+mysql> show create table my_student\G
+*************************** 1. row ***************************
+       Table: my_student
+Create Table: CREATE TABLE `my_student` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci DEFAULT NULL,
+  `class_id` int(11) DEFAULT NULL,
+  `age` int(11) DEFAULT NULL,
+  `gender` int(11) DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `fk_class_id` (`class_id`),
+  CONSTRAINT `fk_class_id` FOREIGN KEY (`class_id`) REFERENCES `my_class` (`id`)
+) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+```
+
+### 1.2、删除外键
+
+外键不允许修改，只能先删除再添加
+
+```sql
+alter table 从表 drop foreign key 外键名字;
+```
+
+示例
+
+```sql
+alter table my_student drop foreign key `fk_class_id`;
+
+mysql> show create table my_student\G
+*************************** 1. row ***************************
+       Table: my_student
+Create Table: CREATE TABLE `my_student` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci DEFAULT NULL,
+  `class_id` int(11) DEFAULT NULL,
+  `age` int(11) DEFAULT NULL,
+  `gender` int(11) DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `fk_class_id` (`class_id`)
+) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+```
+
+外键不会删除普通索引，只会删除外键
+
+删除普通索引
+```sql
+alter table 表名 drop index 索引名字;
+```
+
+### 1.3、外键的基本要求
+
+1. 外键字段需要与关联的主表的主关键字段类型完全一致
+2. 基本属性也要相同
+3. 如果是表后增加外键，对数据还有一定的要求（从表数据与主表的关联关系）
+4. 外键只能使用innodb存储引擎，myisam不支持
+
+## 2、外键约束
+
+外键约束：通过建立外键关系后，对主表和从表都会有一定的数据约束效律
+
+### 2.1、约束的基本概念
+
+当外键产生时，外键所在的表（从表）会受制于主表数据的存在，从而导致数据不能进行某些不符合规范的操作
+不能插入主表不存在的数据
+
+如果一张表被其他表外键引入，那么该表的数据操作不能随意，必须保证从表数据的有效性，不能随意删除一个被从表引入的记录
+
+```sql
+mysql> select * from my_class;
++----+--------+
+| id | name   |
++----+--------+
+|  1 | 一班   |
+|  3 | 三班   |
+|  2 | 二班   |
++----+--------+
+
+insert into my_foreign (name, class_id) values ('张飞', 1);
+Query OK, 1 row affected (0.01 sec)
+
+-- 主表没有id=4的记录，从表不能插入该数据
+insert into my_foreign (name, class_id) values ('张飞', 4);
+ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`mydatabase`.`my_foreign`, CONSTRAINT `my_foreign_ibfk_1` FOREIGN KEY (`class_id`) REFERENCES `my_class` (`id`))
+
+mysql> select * from my_foreign;
++----+--------+----------+
+| id | name   | class_id |
++----+--------+----------+
+|  1 | 张飞   |        1 |
++----+--------+----------+
+1 row in set (0.00 sec)
+
+-- 从表中引用了id=1的记录，该数据不能被删除
+delete from my_class where id = 1;
+ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`mydatabase`.`my_foreign`, CONSTRAINT `my_foreign_ibfk_1` FOREIGN KEY (`class_id`) REFERENCES `my_class` (`id`))
+
+```
+### 2.2、外键约束的概念
+
+基本语法
+
+```sql
+add foreign key (外键字段) references 主表(主键) on 约束模式;
+```
+
+约束模式有三种
+
+- district  严格模式 默认，不允许操作
+- cascade  级联模式，一起操作，主表变化，从表的数据也跟着变化
+- set null 置空模式 主表变化（删除）,从表对应记录设置，前提是从表中对应的外键字段允许为空
+
+外键约束的主要对象是主表操作，从表就是不能插入主表不存在的数据
+
+通常在进行约束的时候，需要制定操作，update 和 delete
+
+常用的模式
+```sql
+-- 更新级联, 删除置空, 空格隔开
+on update cascade on delete set null;
+```
+
+```sql
+-- 增加约束模式
+alter table my_student
+add foreign key (class_id) references my_class(id)
+on update cascade on delete set null;
+
+mysql> show create table my_student\G
+*************************** 1. row ***************************
+       Table: my_student
+Create Table: CREATE TABLE `my_student` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `name` varchar(10) COLLATE utf8mb4_general_ci DEFAULT NULL,
+  `class_id` int(11) DEFAULT NULL,
+  `age` int(11) DEFAULT NULL,
+  `gender` int(11) DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `class_id` (`class_id`),
+  CONSTRAINT `my_student_ibfk_1` FOREIGN KEY (`class_id`) REFERENCES `my_class` (`id`) ON DELETE SET NULL ON UPDATE CASCADE
+) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
+
+mysql> select * from my_class;
++----+--------+
+| id | name   |
++----+--------+
+|  1 | 一班   |
+|  3 | 三班   |
+|  2 | 二班   |
++----+--------+
+3 rows in set (0.00 sec)
+
+mysql> select * from my_student;
++----+--------+----------+------+--------+
+| id | name   | class_id | age  | gender |
++----+--------+----------+------+--------+
+|  1 | 刘备   |        1 |   18 |      2 |
+|  2 | 李四   |        1 |   19 |      1 |
+|  3 | 王五   |        2 |   20 |      2 |
+|  4 | 张飞   |        2 |   21 |      1 |
+|  5 | 关羽   |     NULL |   22 |      2 |
+|  6 | 曹操   |        1 |   20 |   NULL |
++----+--------+----------+------+--------+
+6 rows in set (0.00 sec)
+
+-- 更新主表
+update my_class set id = 4 where id = 2;
+
+-- 从表中所有class_id=2 的记录被修改为了 class_id=4
+mysql> select * from my_student;
++----+--------+----------+------+--------+
+| id | name   | class_id | age  | gender |
++----+--------+----------+------+--------+
+|  1 | 刘备   |        1 |   18 |      2 |
+|  2 | 李四   |        1 |   19 |      1 |
+|  3 | 王五   |        4 |   20 |      2 |
+|  4 | 张飞   |        4 |   21 |      1 |
+|  5 | 关羽   |     NULL |   22 |      2 |
+|  6 | 曹操   |        1 |   20 |   NULL |
++----+--------+----------+------+--------+
+
+
+-- 删除主表数据
+delete from  my_class where id = 4;
+
+-- 从表中记录class_id=4被修改为class_id=null;
+mysql> select * from my_student;
++----+--------+----------+------+--------+
+| id | name   | class_id | age  | gender |
++----+--------+----------+------+--------+
+|  1 | 刘备   |        1 |   18 |      2 |
+|  2 | 李四   |        1 |   19 |      1 |
+|  3 | 王五   |     NULL |   20 |      2 |
+|  4 | 张飞   |     NULL |   21 |      1 |
+|  5 | 关羽   |     NULL |   22 |      2 |
+|  6 | 曹操   |        1 |   20 |   NULL |
++----+--------+----------+------+--------+
+6 rows in set (0.00 sec)
+```
+
+### 2.3、约束的作用
+
+保证数据的完整性，主表与从表的数据要一致
+
+正是因为外键有非常强大的数据约束作用，而且可能导致数据再后台变化的不可控性，导致程序在设计开发逻辑的时候，没有办法很好的把握数据，所以外键很少使用
+
diff --git a/blog/php-mysql/sql-power.md b/blog/php-mysql/sql-power.md
index 394a5a19c88cdbaf357dc34d1cb7a2c984593686..76e5d3264e640e23ada7adeef48eed58c468d2c1 100644
--- a/blog/php-mysql/sql-power.md
+++ b/blog/php-mysql/sql-power.md
@@ -231,6 +231,3 @@ alter user 'root'@'localhost' identified by '123456';
 ```
 
 修改完后，关闭mysql服务器，重启
-
-
-https://www.bilibili.com/video/BV1Vx411g7uJ?p=57&spm_id_from=pageDriver
\ No newline at end of file
diff --git a/blog/php-mysql/sql-view.md b/blog/php-mysql/sql-view.md
new file mode 100644
index 0000000000000000000000000000000000000000..7e9240f4ecc853a0ae8816cafc0eec713f2464ee
--- /dev/null
+++ b/blog/php-mysql/sql-view.md
@@ -0,0 +1,123 @@
+# 视图 view
+
+## 1、创建视图
+
+视图本质是SQL指令
+
+基本语法
+
+```sql
+-- 可以是单表数据，也可以是连接查询，联合查询或子查询
+create view 视图名字 as select 指令
+```
+
+示例
+
+```sql
+mysql> select * from my_student;
++----+--------+----------+------+--------+
+| id | name   | class_id | age  | gender |
++----+--------+----------+------+--------+
+|  1 | 刘备   |        1 |   18 |      2 |
+|  2 | 李四   |        1 |   19 |      1 |
+|  3 | 王五   |     NULL |   20 |      2 |
+|  4 | 张飞   |     NULL |   21 |      1 |
+|  5 | 关羽   |     NULL |   22 |      2 |
+|  6 | 曹操   |        1 |   20 |   NULL |
++----+--------+----------+------+--------+
+6 rows in set (0.00 sec)
+
+mysql> select * from my_class;
++----+--------+
+| id | name   |
++----+--------+
+|  1 | 一班   |
+|  3 | 三班   |
++----+--------+
+2 rows in set (0.00 sec)
+
+-- 创建视图
+create view student_class_view as 
+select s.*, c.name class_name from my_student as s 
+left join my_class as c
+on s.class_id = c.id;
+```
+
+查看视图结构，视图本身是虚拟表，所以关于表的操作都适用于视图
+
+```sql
+show tables;
+show create view <table_name>;
+desc <table_name>;
+```
+
+## 2、使用视图
+
+视图是一张虚拟表，可以直接把视图当做表操作，视图本身没有数据，是临时执行select语句得到对应的结果，视图主要用于查询操作
+
+基本语法
+```sql
+select 字段列表 from 视图名字 [子句];
+```
+
+示例
+
+```sql
+select * from student_class_view;
++----+--------+----------+------+--------+------------+
+| id | name   | class_id | age  | gender | class_name |
++----+--------+----------+------+--------+------------+
+|  1 | 刘备   |        1 |   18 |      2 | 一班       |
+|  2 | 李四   |        1 |   19 |      1 | 一班       |
+|  3 | 王五   |     NULL |   20 |      2 | NULL       |
+|  4 | 张飞   |     NULL |   21 |      1 | NULL       |
+|  5 | 关羽   |     NULL |   22 |      2 | NULL       |
+|  6 | 曹操   |        1 |   20 |   NULL | 一班       |
++----+--------+----------+------+--------+------------+
+6 rows in set (0.00 sec)
+```
+
+## 3、修改视图
+
+本质是修改视图对应的查语句
+
+基本语法
+```sql
+alter view 视图名字 as select 语句;
+```
+
+示例
+
+```sql
+alter view student_class_view as 
+select s.id, s.name, c.name class_name from my_student as s 
+left join my_class as c
+on s.class_id = c.id;
+
+mysql> select * from student_class_view;
++----+--------+------------+
+| id | name   | class_name |
++----+--------+------------+
+|  1 | 刘备   | 一班       |
+|  2 | 李四   | 一班       |
+|  3 | 王五   | NULL       |
+|  4 | 张飞   | NULL       |
+|  5 | 关羽   | NULL       |
+|  6 | 曹操   | 一班       |
++----+--------+------------+
+```
+
+## 4、删除视图
+
+基本语法
+
+```sql
+drop view 视图名字;
+```
+
+示例
+```sql
+drop view student_class_view;
+```
+
+https://www.bilibili.com/video/BV1Vx411g7uJ?p=60&spm_id_from=pageDriver
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