創建觸發器影響特定行

Question

我希望它做的是在新的行或第B現有行的編輯任何插入，具體的「last_seen」列將在A.更新

這是我到目前爲止：

CREATE TRIGGER insert_records 
AFTER UPDATE ON loan_records 
FOR EACH ROW 
Update temp_card A 
INNER JOIN loan_records B 
SET A.last_seen = CURRENT_TIMESTAMP 
WHERE A.card_no = B.card_no 

這

CREATE TRIGGER insert_records2 
AFTER INSERT ON loan_records 
FOR EACH ROW 
Update temp_card A 
INNER JOIN loan_records B 
SET A.last_seen =CURRENT_TIMESTAMP 
WHERE A.card_no = B.card_no 

目前該更新一所有「last_seen」欄目，他們不管是否已經更新。

Answer 1

你不需要JOIN兩個表。只需在UPDATE語句的WHERE子句中使用NEW.card_no即可。

下面是兩個（AFTER INSERT和AFTER UPDATE）的觸發器可能看起來像

CREATE TRIGGER tg_loan_records_insert 
AFTER INSERT ON loan_records 
FOR EACH ROW 
    UPDATE temp_card 
    SET last_seen = NOW() 
    WHERE card_no = NEW.card_no; 

CREATE TRIGGER tg_loan_records_update 
AFTER UPDATE ON loan_records 
FOR EACH ROW 
    UPDATE temp_card 
    SET last_seen = NOW() 
    WHERE card_no = NEW.card_no; 

下面是SQLFiddle演示

Answer 2

您應該只引用當前更新的ID。

CREATE TRIGGER insert_records2 
AFTER INSERT ON loan_records 
FOR EACH ROW 
Update temp_card A 
INNER JOIN loan_records B 
SET A.last_seen =CURRENT_TIMESTAMP 
WHERE A.card_no = B.card_no and a.id = OLD.id 

有關如何更新之前，使用更多的細節，更新後請參閱

http://dev.mysql.com/doc/refman/5.0/en/create-trigger.html