SQL增删改

USE sqlxx
CREATE TABLE ygb(
        sid INT,
        sname VARCHAR(20),
        sgender VARCHAR(2),
        sbirthday DATE,
        semail VARCHAR(10),
        sremark VARCHAR(50)
        )
 DESC ygb;
 SELECT * FROM ygb;
 /*增加age列*/
 ALTER TABLE ygb ADD COLUMN sage INT;
 /*改变age列的属性为int*/
 ALTER TABLE ygb MODIFY COLUMN sage INT;
 /*将email的varchar改为50*/
 ALTER TABLE ygb MODIFY COLUMN semail VARCHAR(50);
 /*删除remark列*/
 ALTER TABLE ygb DROP COLUMN sremark;
 /*将name的名字改为username*/
 ALTER TABLE ygb CHANGE COLUMN sname username VARCHAR(20)
 /*在列中添加数据，按顺序来*/
 INSERT INTO ygb VALUES(123,‘韩凯‘,‘男‘,‘2018-05-01‘,‘1051765559@qq.com‘,27)
 INSERT INTO ygb VALUES(213,‘小韩‘,‘男‘,‘2018-01-01‘,‘1051765558@qq.com‘,24)
 INSERT INTO ygb VALUES(312,‘小张‘,‘男‘,‘2018-03-17‘,‘1051765557@qq.com‘,25)
 /*删除id为213的那一行*/
 DELETE FROM ygb WHERE sid=213;
 DELETE FROM ygb WHERE username=‘韩凯‘;
 /*将id为312的行性别改为女、名字改为张乐*/
 UPDATE ygb SET sgender=‘女‘,username=‘张乐‘ WHERE sid=312;