插入后和更新后的MySQL触发器 [英] MySQL trigger after insert and after update

问题描述

我有两个表，其中一个名为att，如下所示

CREATE TABLE att (
  SID varchar(50) NOT NULL, 
  CID varchar(50) NOT NULL, 
  Date date NOT NULL,
  H1 varchar(1) NOT NULL DEFAULT 0,
  H2 varchar(1) NOT NULL DEFAULT 0,
  H3 varchar(1) NOT NULL DEFAULT 0,
  H4 varchar(1) NOT NULL DEFAULT 0,
  H5 varchar(1) NOT NULL DEFAULT 0,
  H6 varchar(1) NOT NULL DEFAULT 0,
  H7 varchar(1) NOT NULL DEFAULT 0,
  H8 varchar(1) NOT NULL DEFAULT 0,
  H9 varchar(1) NOT NULL DEFAULT 0,
  H10 varchar(1) NOT NULL DEFAULT 0,
  INDEX (SID, CID)
);

另一个表是per，其中包含以下字段:
SID CID Per

如何为以下内容编写触发器:
如果att表中h1-h0的任何字段中发生更新，则
使用以下值更新per表中的per列:
(((总计1s-总计0s)/((总计1s +总计0s))/100

预先感谢
我开发了一个触发器，但是它不起作用，它在第11行说了错误，您能说出什么问题吗?

create TRIGGER `att_up` AFTER UPDATE ON `attentance`
FOR EACH ROW BEGIN
  DECLARE Zeros INT;
  DECLARE Ones INT;
  DECLARE total INT;
  DECLARE atted FLOAT;
  SELECT SUM(8-(h1+h2+h3+h4+h5+h6+h7+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;
  set atted=((ZEROS-Ones)/total)/100;
  INSERT into per(per) values (atted);
END$$

解决方案

在定义触发器之前，请确保更改定界符.还要确保在创建表和触发器时使用相同的表名和列名(在示例中，您使用的是att和attendance以及SID和StudID).

就这样，设置分隔符后，在MySQL 5.1.55中对触发器定义进行测试时，触发器定义没有引起错误.

delimiter $$
CREATE TRIGGER `att_up` 
  AFTER UPDATE ON `attendance`
FOR EACH ROW 
BEGIN
  DECLARE Zeros INT;
  DECLARE Ones INT;
  DECLARE total INT;
  DECLARE attend FLOAT;
  SELECT SUM(8-(h1+h2+h3+h4+h5+h6+h7+h8)), 
         SUM(h1+h2+h3+h4+h5+h6+h7+h8),
         SUM(8-(h1+h2+h3+h4+h5+h6+h7+h8)) + SUM(h1+h2+h3+h4+h5+h6+h7+h8)
    INTO Zeros, Ones, Total FROM attendance 
    WHERE SID=NEW.SID;
  SET attend=((Zeros-Ones)/total)/100;
  INSERT INTO per (SID, CID, per) values (NEW.SID, NEW.CID, attend)
    ON DUPLICATE KEY UPDATE per=attend;
END$$
delimiter ;

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 NULL,
  H1 varchar(1) NOT NULL DEFAULT 0,
  H2 varchar(1) NOT NULL DEFAULT 0,
  H3 varchar(1) NOT NULL DEFAULT 0,
  H4 varchar(1) NOT NULL DEFAULT 0,
  H5 varchar(1) NOT NULL DEFAULT 0,
  H6 varchar(1) NOT NULL DEFAULT 0,
  H7 varchar(1) NOT NULL DEFAULT 0,
  H8 varchar(1) NOT NULL DEFAULT 0,
  H9 varchar(1) NOT NULL DEFAULT 0,
  H10 varchar(1) NOT NULL DEFAULT 0,
  INDEX (SID, CID)
);

The other table is per with following fields:
SID CID Per

How do I write a trigger for the following:
If an update occurs in any of the fields from h1-h0 on att table then
update the per column in the per table with the following values:
((total no of 1s - total no of 0s)/(total no of 1s + total no of 0s))/100

Thanks in advance
i Developed a Trigger,but it not working,its saying error in line 11,can you say what is the problem??

create TRIGGER `att_up` AFTER UPDATE ON `attentance`
FOR EACH ROW BEGIN
  DECLARE Zeros INT;
  DECLARE Ones INT;
  DECLARE total INT;
  DECLARE atted FLOAT;
  SELECT SUM(8-(h1+h2+h3+h4+h5+h6+h7+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;
  set atted=((ZEROS-Ones)/total)/100;
  INSERT into per(per) values (atted);
END$$

解决方案

Make sure you change the delimiter before defining the trigger. Also make sure you're using the same table and column names when you create the table and the trigger (you're using att and attendance, and SID and StudID, in your examples).

As it is, the trigger definition caused no error when I tested it in MySQL 5.1.55 after setting the delimiter.

delimiter $$
CREATE TRIGGER `att_up` 
  AFTER UPDATE ON `attendance`
FOR EACH ROW 
BEGIN
  DECLARE Zeros INT;
  DECLARE Ones INT;
  DECLARE total INT;
  DECLARE attend FLOAT;
  SELECT SUM(8-(h1+h2+h3+h4+h5+h6+h7+h8)), 
         SUM(h1+h2+h3+h4+h5+h6+h7+h8),
         SUM(8-(h1+h2+h3+h4+h5+h6+h7+h8)) + SUM(h1+h2+h3+h4+h5+h6+h7+h8)
    INTO Zeros, Ones, Total FROM attendance 
    WHERE SID=NEW.SID;
  SET attend=((Zeros-Ones)/total)/100;
  INSERT INTO per (SID, CID, per) values (NEW.SID, NEW.CID, attend)
    ON DUPLICATE KEY UPDATE per=attend;
END$$
delimiter ;

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