本來我是用navicat for mysql 在本地測試，新增觸發器是OK的。

但是在伺服器時 我用phpmyadmin 新增，報語法錯誤，才知道phpmyadmin是新增不了觸發器的。

改用navicat for mysql 工具就可以了

觸發器語法和SQL Server有所不同，變數的賦值之類的，下面是語法案例

DROP TRIGGER IF EXISTS exam_trigger; 
create trigger exam_trigger
after insert on exam
FOR EACH ROW
BEGIN 
		DECLARE peoplecount int;
		DECLARE newclasssize int;
		DECLARE newmodifycount int;
		select count(*) INTO peoplecount from exam where examschool = NEW.examschool and examnum = NEW.examnum;
		select classsize,modifycount INTO newclasssize,newmodifycount from examschool where eschool = NEW.examschool;
		
		IF(peoplecount = newclasssize*21) THEN
				IF(NEW.examschool='翠竹' || NEW.examschool='園嶺') THEN
						IF(newmodifycount<=1) THEN
								update examschool set classsize=classsize+2,modifycount=modifycount+1 where eschool = NEW.examschool;
						ELSEIF(newmodifycount=2) THEN
								update examschool set classsize=classsize+1,modifycount=modifycount+1 where eschool = NEW.examschool;
						END IF;
				
				ELSEIF(NEW.examschool='蓮花北') THEN
						IF(newmodifycount=0) THEN
								update examschool set classsize=classsize+2,modifycount=modifycount+1 where eschool = NEW.examschool;
						ELSEIF(newmodifycount=1) THEN
								update examschool set classsize=classsize+1,modifycount=modifycount+1 where eschool = NEW.examschool;
						END IF;
				
				ELSEIF(NEW.examschool='益田' && newmodifycount<=2) THEN
						update examschool set classsize=classsize+1,modifycount=modifycount+1 where eschool = NEW.examschool;
				
				ELSEIF(NEW.examschool='景田' && newmodifycount<=4) THEN
						update examschool set classsize=classsize+1,modifycount=modifycount+1 where eschool = NEW.examschool;
				END IF;

		END IF;
END