sql基本操作增删改查

1、新建一个数据库 handsome

create table handsome(name char(10),age decimal,sex char(6) default ‘male’);

create table students like handsome;

2、设置主键

alter table handsome add primary key(name);

3、插入数据

INSERT INTO handsome(NAME,age) VALUES('宋仲基',30); 

INSERT INTO handsome(NAME,age) VALUES('吴亦凡',28); 

INSERT INTO handsome(NAME,age) VALUES('白敬亭',22); 

INSERT INTO handsome(NAME,age) VALUES('王俊凯',18); 

INSERT INTO handsome(NAME,age) VALUES('刘昊然',19); 

INSERT INTO handsome(NAME,age) VALUES('马天宇',30); 

4、查询

SELECT * FROM handsome WHERE NAME = '宋仲基'；  

SELECT * FROM handsome WHERE NAME like  '%宋%'；

SELECT AVG(age) FROM handsome ;

5、增加一列

ALTER TABLE handsome ADD COLUMN Height INT; 

6、删除

DELETE from table handsome where name like '白%'；

DROP TABLE students;