列更改触发器更新

Question

当前你好，我的触发器更新表更新，我需要改变它只在特定列更改时触发。

代码： 创建触发器钱things

for each row 
begin 
UPDATE `current` c 
INNER JOIN things t ON c.id2 = t.id2 
INNER JOIN dude_base d ON d.id1 = c.is1 
SET c.`curr_cash` = t.thing_cost * d.salary/100; 
end; 
$$ 

更新后，我需要改变，因此它会打开，当有来自东西“thing_cost”更新。

@edit 我必须更新curr_cash和东西的成本是完全不同的值，我无法比较它们，它们将永远是不同的。

当我用

if NEW.things_cost <> OLD.things_cost 

我获得以下错误：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 10 

@edit

create trigger wys_sk_b after update on `dude_base` 
for each row 
begin 
if NEW.salary <> OLD.salary 
then 
UPDATE `current` s 
INNER JOIN things u ON s.id_thing = u.id_thing 
INNER JOIN dude_base b ON b.id = s.id 
SET s.`curr_cash` = u.thing_cost * b.salary/ 100; 
end if; 
$$ 

Answer 1

试试这个代码...

**create table sales** (orderno INT, sale INT,empsalary int, ts TIMESTAMP); 

**create table history** (updated varchar(20), oldvalue INT,newvalue INT); 

INSERT INTO **sales** (orderno,sale,empsalary) VALUES(1,700,7000); 

INSERT INTO **sales** (orderno,sale,empsalary) VALUES(2,800,8000); 

INSERT INTO **sales** (orderno,sale,empsalary) VALUES(3,900,9000); 


DROP TRIGGER test.instrigger; 

DELIMITER ///

CREATE TRIGGER test.instrigger AFTER UPDATE ON sales 
FOR EACH ROW 

BEGIN 

    IF NEW.sale <> OLD.sale THEN 
     INSERT INTO history (updated, oldvalue, newvalue) VALUES('sale', OLD.sale,NEW.sale); 

    END IF; 
    IF NEW.empsalary <> OLD.empsalary THEN 
     INSERT INTO history (updated, oldvalue, newvalue) VALUES('empsalary', OLD.empsalary,NEW.empsalary); 
    END IF; 
END; 

///

DELIMITER;

Answer 2

delimiter $$ 
create trigger wys_sk_b after update on `dude_base` 
for each row 
begin 
    if NEW.salary <> OLD.salary 
    then 
    UPDATE `current` s 
    INNER JOIN things u ON s.id_thing = u.id_thing 
    INNER JOIN dude_base b ON b.id = s.id 
    SET s.`curr_cash` = u.thing_cost * b.salary/ 100; 
    end if; 
end; 
$$