mysql表deptno_mysql学习笔记之表的基本操作

创建表

create table 表名

create table if not exists 表名

mysql> create database company;

Query OK, 1 row affected (0.00 sec)

mysql> use company;

Database changed

mysql> create table if not exists t_dept(

-> deptno int,

-> dname varchar(20),

-> loc varchar(40));

Query OK, 0 rows affected (0.20 sec)

mysql> show tables;

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

| Tables_in_company |

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

| t_dept |

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

1 row in set (0.00 sec)

mysql>

显示当前库下的所有表

show tables;

mysql> show tables;

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

| Tables_in_company |

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

| t_dept |

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

1 row in set (0.00 sec)

查看表的结构

describe 表名

简写

desc 表名

mysql> describe t_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

3 rows in set (0.00 sec)

mysql> desc t_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

3 rows in set (0.00 sec)

查看表的详细

show create table 表名

mysql> show create table t_dept;

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

| Table | Create Table |

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

| t_dept | CREATE TABLE `t_dept` (

`deptno` int(11) DEFAULT NULL,

`dname` varchar(20) DEFAULT NULL,

`loc` varchar(40) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8 |

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

1 row in set (0.00 sec)

show create table t_dept \G

mysql> show create table t_dept \G

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

Table: t_dept

Create Table: CREATE TABLE `t_dept` (

`deptno` int(11) DEFAULT NULL,

`dname` varchar(20) DEFAULT NULL,

`loc` varchar(40) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8

1 row in set (0.00 sec)

删除表

drop table 表名

drop table if exists 表名

mysql> drop table if exists t_dept;

Query OK, 0 rows affected (0.12 sec)

mysql> show tables;

Empty set (0.00 sec)

修改表名

ALTER TABLE old_table_name RENAME [TO] new_table_name

old_table_name 原表名

new_table_name 新表名

将t_dept修改为tab_dept

mysql> alter table t_dept rename tab_dept;

Query OK, 0 rows affected (0.09 sec)

mysql> show tables;

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

| Tables_in_company |

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

| tab_dept |

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

1 row in set (0.00 sec)

mysql> desc tab_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

3 rows in set (0.00 sec)

为表增加一个字段默认在最后

ALTER TABLE table_name ADD 属性名属性类型

为tab_dept增加一个字段descri varchar(20)

mysql> desc tab_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

3 rows in set (0.00 sec)

mysql> alter table tab_dept add descri varchar(20);

Query OK, 0 rows affected (0.33 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

4 rows in set (0.00 sec)

在表的第一个位置增加一个字段

ALTER TABLE table_name ADD 属性名属性类型 first

mysql> alter table tab_dept add id int first;

Query OK, 0 rows affected (0.38 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

5 rows in set (0.00 sec)

在表的指定字段之后增加字段

ALTER TABLE table_name ADD 属性名属性类型 AFTER 属性名

mysql> alter table tab_dept add comm varchar(20) after dname;

Query OK, 0 rows affected (0.31 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

6 rows in set (0.00 sec)

删除字段

ALTER TABLE table_name DROP 属性名

mysql> alter table tab_dept drop comm;

Query OK, 0 rows affected (0.32 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

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

5 rows in set (0.00 sec)

字段修改-修改字段数据类型

ALTER TABLE table_name MODIFY 属性名数据类型

mysql> alter table tab_dept modify descri int;

Query OK, 0 rows affected (0.45 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

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

5 rows in set (0.00 sec)

字段修改-修改字段名称

ALTER TABLE table_name CHANGE 旧属性名新属性名旧数据类型

mysql> alter table tab_dept change id deptid int;

Query OK, 0 rows affected (0.07 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| deptid | int(11) | YES | | NULL | |

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

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

5 rows in set (0.00 sec)

字段修改-同时修改字段名称与数据类型

ALTER TABLE table_name CHANGE 旧属性名新属性名新数据类型

mysql> alter table tab_dept change deptid id varchar(32);

Query OK, 0 rows affected (0.49 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| id | varchar(32) | YES | | NULL | |

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

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

5 rows in set (0.00 sec)

修改顺序

ALTER TABLE table_name MODIFY 属性名1 数据类型 FIRST|AFTER 属性名2

2个属性必须存在

将deptno调到第一个位置

mysql> alter table tab_dept modify deptno int first;

Query OK, 0 rows affected (0.33 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| id | varchar(32) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

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

5 rows in set (0.00 sec)

将ID放在最后

mysql> alter table tab_dept modify deptno int after descri;

Query OK, 0 rows affected (0.29 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| id | varchar(32) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

| deptno | int(11) | YES | | NULL | |

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

5 rows in set (0.00 sec)

mysql> alter table tab_dept modify deptno int first;

Query OK, 0 rows affected (0.34 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table tab_dept modify id int after descri;

Query OK, 0 rows affected (0.47 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc tab_dept;

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

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

| deptno | int(11) | YES | | NULL | |

| loc | varchar(40) | YES | | NULL | |

| descri | int(11) | YES | | NULL | |

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

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

5 rows in set (0.00 sec)

mysql表deptno_mysql学习笔记之表的基本操作

悦读