UPDATE `USER` SET username=1 where userId=1;
UPDATE `USER` SET `PASSWORD` = 2 WHERE userId = 2;
SELECT * FROM `USER`;
SELECT * FROM USER WHERE userId = 1;
INSERT INTO `USER`(userid,username,password) VALUES('5','huangzhen','123456789')


SELECT * from `USER`  LIMIT 0,2;


SELECT * from `USER` where 1=1  ORDER BY userId DESC LIMIT 0,2;


create table student(
studentId int PRIMARY key AUTO_INCREMENT,


stuName VARCHAR(20) not null,


stuNO varchar(21) not NULL,


stuAge varchar(2) not null,


buildTime VARCHAR(30) not null,


stuState VARCHAR(1) DEFAULT 0


)


--清空表內的資料，但是自增的主鍵不歸零--    
DELETE from student;
--清空表內的資料，自增的主鍵歸零--
TRUNCATE TABLE student;




SELECT * from student where  stuState=1;


--批量插入第一種方法  效率比較低 同一個時間插入-- 
INSERT INTO 
student(stuName,stuNo,stuAge,buildTime) 
VALUES('張三',123456,18,NOW()),
('張1',1234561,11,NOW()),
('張2',1234562,12,NOW()),
('張3',1234563,13,NOW()),
('張4',1234564,14,NOW()),
('張5',1234565,15,NOW()),
('張6',1234566,16,NOW()),
('張7',1234567,17,NOW()),
('張8',1234568,18,NOW()),
('張9',1234569,18,NOW()),
('張10',12345610,8,NOW()),
('張11',12345611,38,NOW()),
('張12',12345612,48,NOW()),
('張13',12345613,28,NOW()),
('張14',12345614,58,NOW()),
('張15',12345615,18,NOW());


--批量更新
update student set stuState=0 where stuState=1;




SELECT * from student where stuState=1  AND stuName LIKE '%1%' ORDER BY buildTime DESC LIMIT 0,5