MySQL不接受循环结束指令

Question

我正在尝试在插入事件之后创建一个触发器；这是触发器的定义:

 BEGIN
    DECLARE stud INT(11) DEFAULT 0;
    DECLARE cd INT(11) DEFAULT 0;
    DECLARE sw CURSOR FOR 
        (SELECT CodiceStudente FROM Listastudenticorsi WHERE CodiceCorso IN
            (SELECT CodiceCorso FROM Listanews WHERE CodiceNews IN
                (SELECT MAX(Codice) FROM News)));
    DECLARE cod CURSOR FOR
        (SELECT CodiceDocente FROM Listanews WHERE CodiceNews IN
               (SELECT MAX(Codice) FROM News));
    OPEN sw;
    OPEN cod;
    get_loop: LOOP
    FETCH sw INTO stud;
    FETCH cod INTO cd;
    INSERT INTO Inbox(Mittente, Destinatario, Oggetto, Contenuto, Data) VALUES (cd, stud, "Nuova news", "", CURDATE());
    END LOOP get_loop;
END

由于某些原因，MySQL 不允许我创建它:它说我必须检查第 17 行“LOOP; END”附近的语法，但据我所知那里的语法是正确的...我不明白出了什么问题，即使我将循环名称放在结束循环之后，也会出现错误。

我不确定错误是否可能出现在 INSERT 指令中:我不确定变量 @cod 的使用；它始终是一个独特的值，但我不确定这是否是导致问题的原因。如果是这样，我该如何更改该指令才能获得相同的结果？

Answer 1

您缺少第 17 行的 END IF; 语句

BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE stud VARCHAR(255) DEFAULT "";
    DECLARE sw CURSOR FOR 
        (SELECT CodiceStudente FROM Listastudenticorsi WHERE CodiceCorso IN
            (SELECT CodiceCorso FROM Listanews WHERE CodiceNews IN
                (SELECT MAX(Codice) FROM News)));

    SET @cod = (SELECT CodiceDocente FROM Listanews WHERE CodiceNews IN
               (SELECT MAX(Codice) FROM News));
    OPEN sw;
    get_loop: LOOP
    FETCH sw INTO stud;
        IF done THEN
        LEAVE get_loop;
        END IF;
    INSERT INTO Inbox(Mittente, Destinatario, Oggetto, Contenuto, Data) VALUES (@cod, @i, stud, "", CURDATE());
    END LOOP get_loop;
END;