mysql的觸發器出現錯誤

Question

我有這個觸發器，它應該這樣做：

前的新條目在進入日誌表創建，它會從該表中的driver_id，把它放入if語句和然後根據結果將新條目中的允許字段設置爲Y或No。

create trigger xxx before insert on entrylog for each row 
if exists (select * 
       from driver 
       join card_driver 
       on driver.id = card_driver.driver_id 
       join card 
       on card_driver.card_id = card.id 
      where driver.id = new.driver_id) then 
    set new.allowed = 'Y'; 
end if 

唯一的問題是，它的劑量工作。如果我嘗試了把它放到phpMyAdmin的我不斷收到此錯誤：

Error 

SQL query: Documentation 

CREATE trigger allowedupdate before INSERT ON entrylog 
FOR each 
ROW 
IF EXISTS (

SELECT * 
FROM driver 
JOIN card_driver ON driver.id = card_driver.driver_id 
JOIN card ON card_driver.card_id = card.id 
WHERE driver.id = new.driver_id 
) 
THEN 
SET new.allowed = 'Y'; 

MySQL said: Documentation 
#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 9 

if語句是從其中取出，並應產生相同的結果（只是沒有呼應消息）

$sql ="SELECT * 
    FROM driver AS d 
INNER 
    JOIN card_driver AS cd 
    ON cd.driver_id = d.id 
INNER 
    JOIN card AS c 
    ON c.id = cd.card_id  
WHERE d.ID = $id"; 
mysql_select_db('damp'); 
$result = mysql_query($sql, $conn); 
$row = mysql_fetch_assoc($result); 
switch($row['state_id']) 
{ 
case "1": 
    echo "<strong><font color=\"green\">Authorisation Granted!</font></strong>"; 
    break; // This should be a Y , the rest are N 
case "2": 
    echo "<strong><font color=\"red\">Your card has expired and authorisation is denied</font></strong>"; 
    break; 
case "3": 
    echo "<strong><font color=\"red\">Your card has been cancelled and authorisation is denied</font></strong>"; 
    break; 
default: 
    echo "<strong><font color=\"red\">The Card ID does not exist</font></strong>"; 
} 

Answer 1

這是一個非常微妙的問題，但你錯過了最後的end if。它在那裏，但分號結束觸發器定義。這就是爲什麼MySQL有delimiter關鍵字。

觸發定義應該是這樣的：

delimiter $$ 
create trigger xxx before insert on entrylog for each row 
begin 
    if exists (select * 
        from driver 
        join card_driver 
        on driver.id = card_driver.driver_id 
        join card 
        on card_driver.card_id = card.id 
       where driver.id = new.driver_id) then 
     set new.allowed = 'Y'; 
    end if; 
end;$$ 
delimiter ; 

我還添加了begin/end。雖然不是絕對必要的，但我總是使用它們。而且，如果你的原始語句有它們，你將會遇到編譯時錯誤。