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Mysql之DDL语句_create_alter
1.创建数据库mydb1:
mysql>CREATE DATABASE mydb1;
2.在mydb1库中创建表employee:
mysql>CREATE TABLE employee(
id INT,
name VARCHAR(20),
gender VARCHAR(10),
birthday DATE,
entry_date DATE,
job VARCHAR(20),
salary FLOAT(8,2),
resume TEXT ); 3.查看表结构:
mysql>DESC employee;
+-----------------+-----------------+--------+-------+-----------+---------+ | Field | Type | Null | Key | Default | Extra | +-----------------+-----------------+--------+-------+-----------+---------+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | | gender | varchar(10) | YES | | NULL | | | birthday | date | YES | | NULL | | | entry_date | date | YES | | NULL | | | job | varchar(20) | YES | | NULL | | | salary | float(8,2) | YES | | NULL | | | resume | text | YES | | NULL | | +----------------+-----------------+--------+-------+-----------+---------+ 8 rows in set (0.05 sec)
4.在上表的基础上增加一个image列:
mysql>ALTER TABLE employee ADD image BLOB;
5.修改job列,使其长度为60:
mysql>ALTER TABLE employee MODIFY job VARCHAR(60);
6.删除image列:
mysql>ALTER TABLE employee DROP image;
7.修改表名为user(Oracle中是关键字)
1)查看当前库中所有表:
mysql>SHOW TABLES;
2)修改表名:
mysql>RENAME TABLE employee TO user;
8.查看表的创建语句:
mysql>SHOW CREATE TABLE user;
9.列名name修改为username:
mysql>ALTER TABLE user CHANGE name username VARCHAR(20);
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