/*
INSERT
*/
insert (into tablename (columnname, columnname, columnname)
values('','','');

/*MULTIPLE INSERT*/
insert into teacher(teacherID,firstName,lastName,phone,email)
values
('2','Tan','Boon Yong','601235577899','b_t@gmail.com'),
('3','Kuning', 'binti Desa', '60047329457', 'handecand@gmail.com'),
('4','Izzati', 'bin Sri', '60047329457', 'handecand@gmail.com');

/*
UPDATE
*/
update teacher
set phone = ''
where teacherID = 1;


/*
ALTER TABLE
*/
ALTER TABLE `uni`.`classhour`
CHANGE COLUMN `startime` `startime` DATETIME NULL DEFAULT CURRENT_TIMESTAMP ,
CHANGE COLUMN `endtime` `endtime` DATETIME NULL DEFAULT CURRENT_TIMESTAMP ;

ALTER TABLE `uni`.`classhour`
CHANGE COLUMN `weekday` `weekday` ENUM('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday') NULL DEFAULT NULL ;