mysql ddl statement

Mysql DDL statement

- View database tables

show DATABASES;

- Enter the database

use test

--Build a table

CREATE TABLE stu(
id INT PRIMARY KEY NOT NULL AUTO_INCREMENT COMMENT'student number',
sname VARCHAR(255) NOT NULL COMMENT'name',
age TINYINT UNSIGNED NOT NULL DEFAULT 0 COMMENT'age',
gender ENUM('m','f ','n') not null DEFAULT'n
'
COMMENT'Gender ', intime DATETIME not null DEFAULT NOW() COMMENT'Enrollment time' )ENGINE INNODB CHARSET utf8mb4;

- View table

desc stu;

- Error when inserting, adjust sql_mode

SET global sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));

- add column

ALTER TABLE stu ADD qq VARCHAR(20) NOT null DEFAULT '' COMMENT 'qq号';

- Add a column and specify the position of the column

ALTER TABLE stu add wechat VARCHAR(64) NOT NULL UNIQUE DEFAULT '' COMMENT '微信号' AFTER sname;

ALTER TABLE stu ADD num int not null UNIQUE DEFAULT 0 COMMENT'ID' FIRST;

- Delete column

ALTER TABLE stu DROP num;

- Modify column

ALTER TABLE stu MODIFY sname VARCHAR(64) NOT NULL COMMENT '姓名';

ALTER TABLE stu CHANGE gender sex CHAR(4) not null default '' comment '性别';

desc stu;

- Insert data

INSERT into stu VALUES(1,'zs','zs wechat', 18,'m',NOW(),'afdf');

INSERT INTO stu(sname,wechat,age,sex,qq) VALUES('ls','ls wechat',18,'m','ls qq');

-- Inquire

SELECT * from stu;