Mysql的数据表修改操作

程序员文章站 2022-05-30 23:42:58

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1 修改数据表表名

mysql> show tables;
+-------------------+
| Tables_in_test_db |
+-------------------+
| tb_dept1          |
| tb_dept2          |
| tb_emp2           |
| tb_emp3           |
| tb_emp4           |
| tb_emp5           |
| tb_emp6           |
| tb_emp8           |
| tb_empl           |
+-------------------+
9 rows in set (0.00 sec)

mysql> ALTER TABLE tb_emp2 RENAME tb_employ2;
Query OK, 0 rows affected (0.13 sec)

mysql> show tables;
+-------------------+
| Tables_in_test_db |
+-------------------+
| tb_dept1          |
| tb_dept2          |
| tb_emp3           |
| tb_emp4           |
| tb_emp5           |
| tb_emp6           |
| tb_emp8           |
| tb_empl           |
| tb_employ2        |
+-------------------+
9 rows in set (0.00 sec)

mysql>

2 修改数据表字段类型

mysql> desc tb_emp5;
+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id     | int(11)     | NO   | PRI | NULL    |       |
| name   | varchar(25) | YES  |     | NULL    |       |
| deptId | int(11)     | YES  | MUL | NULL    |       |
| salary | float       | YES  |     | NULL    |       |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql> ALTER TABLE tb_emp5 MODIFY name VARCHAR(30);
Query OK, 0 rows affected (0.26 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc tb_emp5;
+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id     | int(11)     | NO   | PRI | NULL    |       |
| name   | varchar(30) | YES  |     | NULL    |       |
| deptId | int(11)     | YES  | MUL | NULL    |       |
| salary | float       | YES  |     | NULL    |       |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql>

3 修改数据表字段名

mysql> DESC tb_dept1;
+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id       | int(11)     | NO   | PRI | NULL    |       |
| name     | varchar(22) | NO   |     | NULL    |       |
| location | varchar(50) | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+
3 rows in set (0.01 sec)

mysql> ALTER TABLE tb_dept1 CHANGE location loc VARCHAR(50);
Query OK, 0 rows affected (0.11 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id    | int(11)     | NO   | PRI | NULL    |       |
| name  | varchar(22) | NO   |     | NULL    |       |
| loc   | varchar(50) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql>

4.1 添加字段（无约束条件）

mysql> DESC tb_dept1;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id    | int(11)     | NO   | PRI | NULL    |       |
| name  | varchar(22) | NO   |     | NULL    |       |
| loc   | varchar(50) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> ALTER TABLE tb_dept1 ADD managerId INT(10);
Query OK, 0 rows affected (0.56 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
4 rows in set (0.18 sec)

mysql>

4.2 添加字段（有约束条件）

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
4 rows in set (0.18 sec)

mysql> ALTER TABLE tb_dept1 ADD column1 VARCHAR(12) NOT NULL;
Query OK, 0 rows affected (0.60 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

mysql>

4.3 添加字段（指定位置1）

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

mysql> ALTER TABLE tb_dept1 ADD column2 INT(11) FIRST;
Query OK, 0 rows affected (0.50 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column2   | int(11)     | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql>

4.4 添加字段（指定位置2）

mysql> ALTER TABLE tb_dept1 ADD column2 INT(11) FIRST;
Query OK, 0 rows affected (0.50 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column2   | int(11)     | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql> ALTER TABLE tb_dept1 ADD column3 INT(11) AFTER name;
Query OK, 0 rows affected (0.54 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column2   | int(11)     | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)

mysql>

5 删除字段

mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column2   | int(11)     | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)

mysql> ALTER TABLE tb_dept1 DROP column2;
Query OK, 0 rows affected (0.76 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql>

6 修改字段排列位置

方式1
mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
| column1   | varchar(12) | NO   |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql>
mysql> ALTER TABLE tb_dept1 MODIFY column1 VARCHAR(12) FIRST;
Query OK, 0 rows affected (0.54 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column1   | varchar(12) | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql>

方式2
mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| column1   | varchar(12) | YES  |     | NULL    |       |
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql> ALTER TABLE tb_dept1 MODIFY column1 VARCHAR(12) AFTER loc;
Query OK, 0 rows affected (0.56 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc tb_dept1;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| id        | int(11)     | NO   | PRI | NULL    |       |
| name      | varchar(22) | NO   |     | NULL    |       |
| column3   | int(11)     | YES  |     | NULL    |       |
| loc       | varchar(50) | YES  |     | NULL    |       |
| column1   | varchar(12) | YES  |     | NULL    |       |
| managerId | int(10)     | YES  |     | NULL    |       |
+-----------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

mysql>

7 更改表的存储引擎

mysql> show create table tb_dept2\G;
*************************** 1. row ***************************
       Table: tb_dept2
Create Table: CREATE TABLE `tb_dept2` (
  `id` int(11) NOT NULL,
  `name` varchar(22) DEFAULT NULL,
  `location` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

ERROR:
No query specified

mysql> ALTER TABLE tb_dept2 ENGINE=MyISAM;
Query OK, 0 rows affected (0.49 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> show create table tb_dept2\G;
*************************** 1. row ***************************
       Table: tb_dept2
Create Table: CREATE TABLE `tb_dept2` (
  `id` int(11) NOT NULL,
  `name` varchar(22) DEFAULT NULL,
  `location` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

ERROR:
No query specified

mysql>

8 删除表的外键约束

mysql> CREATE TABLE tb_emp9
    -> (
    -> id      INT(11) PRIMARY KEY,
    -> name   VARCHAR(25),
    -> deptId  INT(11),
    -> salary   FLOAT,
    -> CONSTRAINT fk_emp_dept  FOREIGN KEY (deptId) REFERENCES tb_dept1(id)
    -> );
Query OK, 0 rows affected (1.36 sec)

mysql>
mysql> SHOW CREATE TABLE tb_emp9\G
*************************** 1. row ***************************
       Table: tb_emp9
Create Table: CREATE TABLE `tb_emp9` (
  `id` int(11) NOT NULL,
  `name` varchar(25) DEFAULT NULL,
  `deptId` int(11) DEFAULT NULL,
  `salary` float DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_emp_dept` (`deptId`),
  CONSTRAINT `fk_emp_dept` FOREIGN KEY (`deptId`) REFERENCES `tb_dept1` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql>



mysql> ALTER TABLE tb_emp9 DROP FOREIGN KEY fk_emp_dept;
Query OK, 0 rows affected (0.10 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SHOW CREATE TABLE tb_emp9\G
*************************** 1. row ***************************
       Table: tb_emp9
Create Table: CREATE TABLE `tb_emp9` (
  `id` int(11) NOT NULL,
  `name` varchar(25) DEFAULT NULL,
  `deptId` int(11) DEFAULT NULL,
  `salary` float DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_emp_dept` (`deptId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql>

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Mysql的数据表修改操作

1 修改数据表表名

2 修改数据表字段类型

3 修改数据表字段名

4.1 添加字段（无约束条件）

4.2 添加字段（有约束条件）

4.3 添加字段（指定位置1）

4.4 添加字段（指定位置2）

5 删除字段

6 修改字段排列位置

7 更改表的存储引擎

8 删除表的外键约束

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