MySQL表操作

1.介绍

　　表就相当于文件，表中的一条记录就相当与文件的一行内容，不同的是，表中的一条记录有对应的标题，成为表的字段。

2.创建表

2.1语法

create table 表名(

字段名1 类型[(宽度) 约束条件],

字段名2 类型[(宽度) 约束条件],

字段名3 类型[(宽度) 约束条件],

);

注意：

    1. 必须进入数据库中才能创建表
    2. 标点符号均为英文标点符号

    3. 在同一张表中，字段名是不能相同的

    4. 宽度和约束条件为可选项

    5. 字段名和类型是必须的

2.2范例

1-使用默认格式创建表

mysql> use python25;

Database changed

mysql> show tables;

Empty set (0.00 sec)

mysql> create table test1(id int,

    -> name char(11),

    -> sex enum('male', 'female'),

    -> hobby set('swiming', 'running', 'basketball'));

Query OK, 0 rows affected (0.02 sec)

mysql> desc test1;

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

| Field | Type                                  | Null | Key | Default | Extra |

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

| id    | int(11)                               | YES  |     | NULL    |       |

| name  | char(11)                              | YES  |     | NULL    |       |

| sex   | enum('male','female')                 | YES  |     | NULL    |       |

| hobby | set('swiming','running','basketball') | YES  |     | NULL    |       |

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

4 rows in set (0.00 sec)

2-自定义格式创建表

# 指定字符编码

mysql> create table test3 (

    -> id int,

    -> name char(10),

    -> age int,

    -> sex enum('male', 'female'),

    -> phone char(11),

    -> job char(10)

    -> ) charset=utf8;

Query OK, 0 rows affected (0.03 sec)

#指定存储引擎

mysql> create table test4 (

    -> id int,

    -> name char(10),

    -> age int,

    -> sex enum('male', 'female'),

    -> phone char(11),

    -> job char(10)

    -> ) ENGINE=MyISAM;

Query OK, 0 rows affected (0.01 sec)

3-查看表结构、创建表的语句

# 查看表结构

mysql> show columns from test1;

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

| Field | Type                                  | Null | Key | Default | Extra |

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

| id    | int(11)                               | YES  |     | NULL    |       |

| name  | char(11)                              | YES  |     | NULL    |       |

| sex   | enum('male','female')                 | YES  |     | NULL    |       |

| hobby | set('swiming','running','basketball') | YES  |     | NULL    |       |

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

4 rows in set (0.00 sec)

mysql> desc test1;

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

| Field | Type                                  | Null | Key | Default | Extra |

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

| id    | int(11)                               | YES  |     | NULL    |       |

| name  | char(11)                              | YES  |     | NULL    |       |

| sex   | enum('male','female')                 | YES  |     | NULL    |       |

| hobby | set('swiming','running','basketball') | YES  |     | NULL    |       |

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

4 rows in set (0.00 sec)

# 查看创建表的语句

mysql> show create table test1 \G;

*************************** 1. row ***************************

       Table: test1

Create Table: CREATE TABLE `test1` (

  `id` int(11) DEFAULT NULL,

  `name` char(11) DEFAULT NULL,

  `sex` enum('male','female') DEFAULT NULL,

  `hobby` set('swiming','running','basketball') DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

1 row in set (0.00 sec)

2.删除表

语法:

DROP TABLE 表名;

注意：删表要谨慎

mysql> show tables;

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

| Tables_in_python25 |

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

| test1              |

| test2              |

| test3              |

| test4              |

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

4 rows in set (0.00 sec)

mysql> drop table test1;

Query OK, 0 rows affected (0.01 sec)

mysql> drop table test2;

Query OK, 0 rows affected (0.01 sec)

mysql> show tables;

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

| Tables_in_python25 |

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

| test3              |

| test4              |

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

2 rows in set (0.00 sec)

3.修改表

3.1 修改表名

语法

ALTER TABLE 表名 RENAME 新表名;

范例

mysql> show tables;

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

| Tables_in_python25 |

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

| test3              |

| test4              |

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

2 rows in set (0.00 sec)

mysql> alter table test3 rename test1;

Query OK, 0 rows affected (0.02 sec)

mysql> show tables;

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

| Tables_in_python25 |

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

| test1              |

| test4              |

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

2 rows in set (0.00 sec)

3.2 增加字段

语法

ALTER TABLE 表名 ADD 字段名数据类型[(宽度) 约束条件], ADD 字段名数据类型[(宽度) 约束条件];

范例

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(10)              | YES  |     | NULL    |       |

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

6 rows in set (0.01 sec)

# 增加hobby、home两个字段

mysql> alter table test1 add hobby set('football', 'running'), add home char(10);

Query OK, 0 rows affected (0.04 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                      | Null | Key | Default | Extra |

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

| id    | int(11)                   | YES  |     | NULL    |       |

| name  | char(10)                  | YES  |     | NULL    |       |

| age   | int(11)                   | YES  |     | NULL    |       |

| sex   | enum('male','female')     | YES  |     | NULL    |       |

| phone | char(11)                  | YES  |     | NULL    |       |

| job   | char(10)                  | YES  |     | NULL    |       |

| hobby | set('football','running') | YES  |     | NULL    |       |

| home  | char(10)                  | YES  |     | NULL    |       |

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

8 rows in set (0.00 sec)

3.3 删除字段

语法

ALTER TABLE 表名 DROP 字段名;

范例

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(10)              | YES  |     | NULL    |       |

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

6 rows in set (0.01 sec)

# 删除hobby、home字段

mysql> alter table test1 add hobby set('football', 'running'), add home char(10);

Query OK, 0 rows affected (0.04 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                      | Null | Key | Default | Extra |

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

| id    | int(11)                   | YES  |     | NULL    |       |

| name  | char(10)                  | YES  |     | NULL    |       |

| age   | int(11)                   | YES  |     | NULL    |       |

| sex   | enum('male','female')     | YES  |     | NULL    |       |

| phone | char(11)                  | YES  |     | NULL    |       |

| job   | char(10)                  | YES  |     | NULL    |       |

| hobby | set('football','running') | YES  |     | NULL    |       |

| home  | char(10)                  | YES  |     | NULL    |       |

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

8 rows in set (0.00 sec)

3.4 修改字段

语法

ALTER TABLE 表名 MODIFY 字段名数据类型[(宽度) 约束条件];

ALTER TABLE 表名 CHANGE 旧字段名新字段名旧数据类型[(宽度) 约束条件];

ALTER TABLE 表名 CHANGE 旧字段名新字段名新数据类型[(宽度) 约束条件];

范例

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(10)              | YES  |     | NULL    |       |

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

6 rows in set (0.00 sec)

# 修改job字段的数据类型

mysql> alter table test1 modify job varchar(11);

Query OK, 0 rows affected (0.06 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | varchar(11)           | YES  |     | NULL    |       |

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

6 rows in set (0.01 sec)

# 修改job字段为hobby字段

mysql> alter table test1 change job hobby varchar(11);

Query OK, 0 rows affected (0.02 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)                   | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| hobby | varchar(11)           | YES  |     | NULL    |       |

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

6 rows in set (0.00 sec)

# 修改hobby字段为job字段，且数据类型改为char

mysql> alter table test1 change hobby job char(11);

Query OK, 0 rows affected (0.06 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(11)              | YES  |     | NULL    |       |

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

6 rows in set (0.01 sec)

3.5 修改字段排列顺序、在增加的时候指定字段位置

语法

ALTER TABLE 表名 ADD 字段名数据类型 [(宽度) 约束条件] FIRST;

ALTER TABLE 表名 ADD 字段名数据类型 [(宽度) 约束条件] AFTER 字段名;

ALTER TABLE 表名 CHANGE 字段名旧字段名新字段名新数据类型 [(宽度) 约束条件] FIRST;

ALTER TABLE 表名 MODIFY 字段名数据类型 [(宽度) 约束条件] AFTER 字段名;

范例

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(11)              | YES  |     | NULL    |       |

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

6 rows in set (0.01 sec)

# 在表的开头添加hobby字段

mysql> alter table test1 add hobby char(10) first;

Query OK, 0 rows affected (0.05 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field | Type                  | Null | Key | Default | Extra |

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

| hobby | char(10)              | YES  |     | NULL    |       |

| id    | int(11)               | YES  |     | NULL    |       |

| name  | char(10)              | YES  |     | NULL    |       |

| age   | int(11)               | YES  |     | NULL    |       |

| sex   | enum('male','female') | YES  |     | NULL    |       |

| phone | char(11)              | YES  |     | NULL    |       |

| job   | char(11)              | YES  |     | NULL    |       |

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

7 rows in set (0.00 sec)

# 在job字段后面添加salary字段

mysql> alter table test1 add salary int after job;

Query OK, 0 rows affected (0.05 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field  | Type                  | Null | Key | Default | Extra |

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

| hobby  | char(10)              | YES  |     | NULL    |       |

| id     | int(11)               | YES  |     | NULL    |       |

| name   | char(10)              | YES  |     | NULL    |       |

| age    | int(11)               | YES  |     | NULL    |       |

| sex    | enum('male','female') | YES  |     | NULL    |       |

| phone  | char(11)              | YES  |     | NULL    |       |

| job    | char(11)              | YES  |     | NULL    |       |

| salary | int(11)               | YES  |     | NULL    |       |

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

8 rows in set (0.00 sec)

# 修改hobby字段名为aihao

mysql> alter table test1 change hobby aihao char(10) first;

Query OK, 0 rows affected (0.02 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field  | Type                  | Null | Key | Default | Extra |

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

| aihao  | char(10)              | YES  |     | NULL    |       |

| id     | int(11)               | YES  |     | NULL    |       |

| name   | char(10)              | YES  |     | NULL    |       |

| age    | int(11)               | YES  |     | NULL    |       |

| sex    | enum('male','female') | YES  |     | NULL    |       |

| phone  | char(11)              | YES  |     | NULL    |       |

| job    | char(11)              | YES  |     | NULL    |       |

| salary | int(11)               | YES  |     | NULL    |       |

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

8 rows in set (0.00 sec)

# 把aihao字段放到salary字段后面

mysql> alter table test1 modify aihao char(10) after salary;

Query OK, 0 rows affected (0.04 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test1;

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

| Field  | Type                  | Null | Key | Default | Extra |

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

| id     | int(11)               | YES  |     | NULL    |       |

| name   | char(10)              | YES  |     | NULL    |       |

| age    | int(11)               | YES  |     | NULL    |       |

| sex    | enum('male','female') | YES  |     | NULL    |       |

| phone  | char(11)              | YES  |     | NULL    |       |

| job    | char(11)              | YES  |     | NULL    |       |

| salary | int(11)               | YES  |     | NULL    |       |

| aihao  | char(10)              | YES  |     | NULL    |       |

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

8 rows in set (0.00 sec)

4.数据操作

创建表

# 创建语句

create table teacher(

id int primary key,

name char(10) not null,

age int,

hire_date datetime,

sex enum('male', 'female') not null default 'male',

phone char(11) unique,

salary float(8, 2),

hobby set('running', 'football', 'basketball'),

comment varchar(255)

);

# 查看表结构

mysql> desc teacher;

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

| Field     | Type                                   | Null | Key | Default | Extra |

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

| id        | int(11)                                | NO   | PRI | NULL    |       |

| name      | char(10)                               | NO   |     | NULL    |       |

| age       | int(11)                                | YES  |     | NULL    |       |

| hire_date | datetime                               | YES  |     | NULL    |       |

| sex       | enum('male','female')                  | NO   |     | male    |       |

| phone     | char(11)                               | YES  | UNI | NULL    |       |

| salary    | float(8,2)                             | YES  |     | NULL    |       |

| hobby     | set('running','football','basketball') | YES  |     | NULL    |       |

| comment   | varchar(255)                           | YES  |     | NULL    |       |

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

9 rows in set (0.00 sec)

4.1 插入数据

语法

插入单行数据，

INSERT INTO 表名 (字段1，字段2，字段3...) value (值1, 值2, 值3);

如果不添加字段名称，插入的数据需要与表里的字段一一对应

INSERT INTO 表名 value (值1, 值2, 值3);

插入多行数据

INSERT INTO 表名 values (值1, 值2, 值3),(值1, 值2, 值3),(值1, 值2, 值3);

范例

#  插入单条数据，注意float类型会进行四舍五入

mysql> insert into teacher (id, name, hobby) value (1, 'zhangsan', 'running');

Query OK, 1 row affected (0.42 sec)

mysql> select * from teacher;

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

| id | name     | age  | hire_date | sex  | phone | salary | hobby   | comment |

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

|  1 | zhangsan | NULL | NULL      | male | NULL  |   NULL | running | NULL    |

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

1 row in set (0.00 sec)

mysql> insert into teacher value (2, 'lisi', 30, '2017-10-20', 'male', '13069948980', 2000, 'basketball', 'haha');

Query OK, 1 row affected (0.15 sec)

mysql> select * from teacher;

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

| id | name     | age  | hire_date           | sex  | phone       | salary  | hobby      | comment |

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

|  1 | zhangsan | NULL | NULL                | male | NULL        |    NULL | running    | NULL    |

|  2 | lisi     |   30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha    |

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

2 rows in set (0.03 sec)

# 插入多条数据

mysql> insert into teacher values (3, 'wangwu', 28, '2016-11-20', 'male', '1382333333', 20000, 'football', 'wowo'),

    ->  (4, 'xiaoli', 28, '2015-11-20', 'female', '13823333333', 20000, 'football', 'wowo');

Query OK, 2 rows affected (0.40 sec)

Records: 2  Duplicates: 0  Warnings: 0

mysql> select * from teacher;

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

| id | name     | age  | hire_date           | sex    | phone       | salary   | hobby      | comment |

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

|  1 | zhangsan | NULL | NULL                | male   | NULL        |     NULL | running    | NULL    |

|  2 | lisi     |   30 | 2017-10-20 00:00:00 | male   | 13069948980 |  2000.00 | basketball | haha    |

|  3 | wangwu   |   28 | 2016-11-20 00:00:00 | male   | 1382333333  | 20000.00 | football   | wowo    |

|  4 | xiaoli   |   28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football   | wowo    |

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

4 rows in set (0.00 sec)

4.2 删除数据

语法

DELETE FROM 表名 WHERE ....;

范例

mysql> select * from teacher;

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

| id | name     | age  | hire_date           | sex    | phone       | salary   | hobby      | comment |

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

|  1 | zhangsan | NULL | NULL                | male   | NULL        |     NULL | running    | NULL    |

|  2 | lisi     |   30 | 2017-10-20 00:00:00 | male   | 13069948980 |  2000.00 | basketball | haha    |

|  3 | wangwu   |   28 | 2016-11-20 00:00:00 | male   | 1382333333  | 20000.00 | football   | wowo    |

|  4 | xiaoli   |   28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football   | wowo    |

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

4 rows in set (0.00 sec)

mysql> delete from teacher where id=1;

Query OK, 1 row affected (0.48 sec)

mysql> select * from teacher;

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

| id | name   | age  | hire_date           | sex    | phone       | salary   | hobby      | comment |

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

|  2 | lisi   |   30 | 2017-10-20 00:00:00 | male   | 13069948980 |  2000.00 | basketball | haha    |

|  3 | wangwu |   28 | 2016-11-20 00:00:00 | male   | 1382333333  | 20000.00 | football   | wowo    |

|  4 | xiaoli |   28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football   | wowo    |

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

3 rows in set (0.00 sec)

4.3 更新数据

语法

UPDATE 表名 SET 字段1=值1, 字段2=值2 WHERE ...;

范例

mysql> select * from teacher;

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

| id | name   | age  | hire_date           | sex    | phone       | salary   | hobby      | comment |

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

|  2 | lisi   |   30 | 2017-10-20 00:00:00 | male   | 13069948980 |  2000.00 | basketball | haha    |

|  3 | wangwu |   28 | 2016-11-20 00:00:00 | male   | 1382333333  | 20000.00 | football   | wowo    |

|  4 | xiaoli |   28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football   | wowo    |

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

3 rows in set (0.00 sec)

mysql> update teacher set age=40 where id=2;

Query OK, 1 row affected (0.46 sec)

Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from teacher;

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

| id | name   | age  | hire_date           | sex    | phone       | salary   | hobby      | comment |

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

|  2 | lisi   |   40 | 2017-10-20 00:00:00 | male   | 13069948980 |  2000.00 | basketball | haha    |

|  3 | wangwu |   28 | 2016-11-20 00:00:00 | male   | 1382333333  | 20000.00 | football   | wowo    |

|  4 | xiaoli |   28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football   | wowo    |

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

3 rows in set (0.00 sec)

4.4 查询数据

单表查询

多表查询

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03-MySQL表操作