MySQL增删改查

1.MySQL安装教程

创建数据库和创建表请看/article/7725421.html

2.登录MySQL

选择zhaochao数据库，并查看user表中字段如下：

3.插入数据

3.1插入方法一

insert into user (id,username,userpasswd) values (3,'赵超','zhaochao');

3.2插入方法二

insert into user values (4,'赵云','zhaoyun');

3.3插入方法三

将自身插入自身

insert into user select * from user;

4.删除字段

4.1删除全部字段

delete from user;

mysql>delete from user;

Query OK, 8 rows affected (0.02 sec)

4.2删除指定字段

delete from user where id=4;

mysql> select * from user;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 1 | admin | admin |

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

| 4 | 赵云 | zhaoyun |

+------+----------+------------+

4 rows in set (0.00 sec)

mysql>delete from user where id=4;

Query OK, 1 row affected (0.03 sec)

mysql> select * from user;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 1 | admin | admin |

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

+------+----------+------------+

3 rows in set (0.00 sec)

5.修改字段内容

update user set username='root' where id=1;

mysql> select * from user;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 1 | admin | admin |

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

+------+----------+------------+

3 rows in set (0.00 sec)

mysql>update user set username='root' where id=1;

Query OK, 1 row affected (0.03 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> select * from user;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 1 | root | admin |

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

+------+----------+------------+

3 rows in set (0.00 sec)

6.查询

6.1查询一

select id,username,userpasswd from user;

mysql>select id,username,userpasswd from user;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 1 | root | admin |

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

+------+----------+------------+

3 rows in set (0.00 sec)

6.2查询二

select id '用户编号',username '用户名',userpasswd '密码' from user a where a.id=1 ;

mysql>select id '用户编号',username '用户名',userpasswd '密码' from user a where a.id=1 ;

+----------+--------+-------+

| 用户编号 | 用户名 | 密码 |

+----------+--------+-------+

| 1 | root | admin |

+----------+--------+-------+

1 row in set (0.00 sec)

6.1查询三

select id,username,userpasswd from user limit 1,2;

mysql>select id,username,userpasswd from user limit 1,2;

+------+----------+------------+

| id | username | userpasswd |

+------+----------+------------+

| 2 | zhaochao | zhaochao |

| 3 | 赵超 | zhaochao |

+------+----------+------------+

2 rows in set (0.00 sec)