mysql SQL语言-创建/查看/删除/清空表

一、创建表

1、创建简单表

CREATE TABLE `student` (
  `id` int(4) NOT NULL,
  `name` char(20) NOT NULL,
  `age` tinyint(2) NOT NULL DEFAULT '0',
  `dept` varchar(16) DEFAULT NULL
) ；

2、创建主键自增长的表

 create table student( 
 	id bigint(20) primary key auto_increment,
 	name char(20) not null,
   	age tinyint(2) not null default 0,
    dept varchar(16) default null
 ); 

3、查看表结构

3.1 方式一：

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | bigint(20)  | NO   | PRI | NULL    | auto_increment |
| name  | char(20)    | NO   |     | NULL    |                |
| age   | tinyint(2)  | NO   |     | 0       |                |
| dept  | varchar(16) | YES  |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

3.2 方式二：

mysql> show columns from student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | bigint(20)  | NO   | PRI | NULL    | auto_increment |
| name  | char(20)    | NO   |     | NULL    |                |
| age   | tinyint(2)  | NO   |     | 0       |                |
| dept  | varchar(16) | YES  |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

4、查看建表语句

mysql> show create table student\G;
*************************** 1. row ***************************
       Table: student
Create Table: CREATE TABLE `student` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `name` char(20) NOT NULL,
  `age` tinyint(2) NOT NULL DEFAULT '0',
  `dept` varchar(16) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

二、删除表

1、删除表

mysql> drop table student;
Query OK, 0 rows affected (0.00 sec

三、清空表

1、清空表命令

mysql> truncate student;
Query OK, 0 rows affected (0.00 sec)