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;
 /*改變age列的屬性為int*/
 ALTER TABLE ygb MODIFY COLUMN sage INT;
 
 
/*將email的varchar改為50*/
 ALTER TABLE ygb MODIFY COLUMN semail VARCHAR(50);
 /*刪除remark列*/
 ALTER TABLE ygb DROP COLUMN sremark;
 /*將name的名字改為username*/
 ALTER TABLE ygb CHANGE COLUMN sname username VARCHAR(20)
 /*在列中添加數據，按順序來*/
 INSERT INTO ygb VALUES(123,‘韓凱‘,‘男‘,‘2018-05-01‘,‘[email protected]‘,27)
 INSERT INTO ygb VALUES(
 
213,‘小韓‘,‘男‘,‘2018-01-01‘,‘[email protected]‘,24)
 INSERT INTO ygb VALUES(312,‘小張‘,‘男‘,‘2018-03-17‘,‘[email protected]‘,25)
 /*刪除id為213的那一行*/
 DELETE FROM ygb WHERE sid=213;
 DELETE FROM ygb WHERE username=‘韓凱‘;
 /*將id為312的行性別改為女、名字改為張樂*/
 UPDATE ygb SET sgender=‘女‘,username=‘張樂‘ WHERE sid=312;

SQL增刪改