寫入觸發器語句時出錯

Question

我想將表的大小限制爲X行（例如，我將使用5）。達到限制時，我想將最舊的行復制到另一個表中，然後將其刪除。我目前有：

CREATE TRIGGER LimitRows BEFORE INSERT ON MyTable 
FOR EACH ROW BEGIN 
    IF (SELECT COUNT(*) FROM MyTable) >= 5 THEN 

    INSERT INTO HistoryTable 
    SELECT * 
    FROM MyTable A 
    WHERE vhID = A.min(vhID); 

    DELETE FROM MyTable 
    WHERE vhID = min(vhID); 

    END IF;  
END; 

目前，我得到的錯誤：

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 8

如何正確地寫這個觸發器？另外，如果將表格從100行開始，我怎樣才能將表格裁剪成5行？

Answer 1

您需要更改分隔符第一

delimiter | 
CREATE TRIGGER LimitRows BEFORE INSERT ON MyTable 
FOR EACH ROW BEGIN 
    IF (SELECT COUNT(*) FROM MyTable) >= 5 THEN 

    INSERT INTO HistoryTable 
    SELECT * 
    FROM MyTable A 
    WHERE vhID = A.min(vhID); 

    DELETE FROM MyTable 
    WHERE vhID = min(vhID); 

    END IF;  
END 
| 
delimiter ; 

否則觸發器定義將結束在第一;這將使其不完整的。