MySQL trigger after insert and after update

Question

I have two tables with one named att as follows

CREATE TABLE att (
  SID varchar(50) NOT NULL, 
  CID varchar(50) NOT NULL, 
  Date date NOT         


        

Answer 1

DELIMITER $$

CREATE TRIGGER `att_up` AFTER UPDATE ON `attentance`
FOR EACH ROW

BEGIN

SET @zeros = 0;
SET @ones = 0;
SET @total = 0;
SET @atted = 0;


(SELECT (8-SUM(h1)+SUM(h2)+SUM(h3)+SUM(h4)+SUM(h5)+SUM(h6)+SUM(h7)+SUM(h8)) INTO @zeros FROM attentance WHERE StudID=NEW.StudID);
(SELECT SUM(h1+h2+h3+h4+h5+h6+h7+h8) INTO @ones FROM attentance WHERE StudID=NEW.StudID);
(SELECT (SUM(8-(h1+h2+h3+h4+h5+h6+h7+h8))+ SUM(h1+h2+h3+h4+h5+h6+h7+h8)) INTO @total FROM attentance WHERE StudID=NEW.StudID);

SELECT (((@zeros-@ones)/@total)/100) INTO @atted FROM (SELECT 1) AS x;

END$$