[MYSQL][1]创建，修改，删除表

SHOW DATABASES;

CREATE DATAABASE mydb;

DROP DATABASE mydb;

SHOW TABLES;

CREATE TABLE test (id INT,
name VARCHAR(20),
sex BOOLEAN
);

 DROP TABLE mytb;

DESC TABLE mytb;

SHOW CREATE TABLE mytb; //查看详细信息

CREATE TABLE mytb1 (id INT PRIMARY KEY,
name VARCHAR(20),
sex BOOLEAN
) //常见单字段主键


CREATE TABLE mytb2 (id INT,
name VARCHAR(20),
sex BOOLEAN,
PRIMARY KEY(id,name)
)//创建多字段主键，id,nane两者的组合可以确定唯一的一条记录

CREATE TABLE mytb3 (id INT,
name VARCHAR(20),
sex BOOLEAN,
CONSTRAINT c_fk FOREIGN KEY(id,name)
    REFERENCES mytb2(id,name)
)

ALTER TABLE user DROP FOREIGN KEY c_fk;

ALTER TABLE mytb3 RENAME user; //修改表名

ALTER TABLE user MODIFY sex  VARCHAR(30);// 修改字段数据类型

ALTER TABLE user CHANGE sex course INT;//修改字段名；旧属性名，新属性名，新数据类型

ALTER TABLE user ADD course_id INT NOT NULL FIRST[AFTER 属性名];

ALTER TABLE user DROP course_id;

ALTER TABLE user     MODIFY name  VARCHAR(20) AFTER course;// 旧字段位置需要带上数据类型

ALTER TABLE user ENGINE=MyISAM;