Question

我在兽医诊所的数据库中创建了一个程序，该程序显示的是：第一次约会，第一次获得兽医授权执行所要求的服务（不得在同一时间预约其他约会）时间）。但是，当我调用此过程时，光标停止，因为eof的值为1，但它并没有真正看到所有记录：光标在行结束前离开循环！我不明白为什么。这是代码：

DELIMITER //

DROP PROCEDURE IF EXISTS first_booking_available //

CREATE PROCEDURE first_booking_available(IN Perf VARCHAR(30), IN DateP DATE)
BEGIN
DECLARE IdV, eof INTEGER;
DECLARE Dat DATE; 
DECLARE i, TimeB, End TIME;

DECLARE vet CURSOR FOR E.Id_vet, W.Date, S.Start_time, S.End_time
                   FROM   Enabled E, Work W, WorkShift S
                   WHERE  E.Code_performance = Perf AND W.Id_vet = E.Id_vet AND S.Code = W.Code_workshift AND W.Date >= DateP ORDER BY  W.Date, S.Start_time;

DECLARE CONTINUE HANDLER FOR NOT FOUND SET eof = 1;

SELECT Duration INTO @Duration FROM Perfomance WHERE Code = Perf;

SET @Start_time = NULL;

OPEN vet;

read_loop: LOOP

    FETCH vet INTO IdV, Dat, TimeB, End;

    IF (eof = 1 OR @Start_time IS NOT NULL) THEN

        LEAVE read_loop;

    END IF;

        SET i = TimeB;

        WHILE i < End AND @Start_time IS NULL DO

            SET @P = NULL;
            SET @F = NULL;

            SELECT ADDTIME(ADDTIME(B.Start_time, P.Duration), '00:01:00') INTO @P
            FROM   Booking B, Performance P
            WHERE  P.Code = B.Code_performance AND B.Date = Dat AND B.Id_vet = IdV AND B.Start_time = i;

            SELECT ADDTIME(ADDTIME(B.Start_time, P.Duration), '00:01:00') INTO @F
            FROM   Booking B, Performance P 
            WHERE  P.Code = B.Code_performance AND B.Date = Dat AND B.Id_vet = IdV AND B.Start_time BETWEEN i AND ADDTIME(i, @Duration) ORDER BY ADDTIME(B.Start_time, P.Duration) DESC LIMIT 1;

            IF @P IS NOT NULL THEN
                SET i = @P;
            END IF;

            IF @F IS NOT NULL THEN
                SET i = @F;
            END IF;            


            IF ADDTIME(i, @duration) > End THEN 
                SET i = End;
            END IF; 

            IF ((@P IS NULL) AND (@F IS NULL) AND (i != End)) THEN
                SET @Start_Time = i;     
            END IF; 

        END WHILE;

        IF @Start_Time IS NOT NULL THEN
            SET @Id_vet = IdV;
            SET @Date = Dat;
        END IF;

END LOOP;

CLOSE vet;

IF @Start_Time IS NULL THEN
    SIGNAL sqlstate '99994'
    SET MESSAGE_TEXT = 'there is no availability !';    
END IF;

END //

DELIMITER ;

Answer 1

DECLARE CONTINUE HANDLER FOR NOT FOUND SET eof = 1;

表示您的查询没有结果。它不仅仅适用于光标，也适用于另一个选择查询。

SELECT ADDTIME(ADDTIME(B.Start_time, P.Duration), '00:01:00') INTO @P
        FROM   Booking B, Performance P
        WHERE  P.Code = B.Code_performance AND B.Date = Dat AND B.Id_vet = IdV AND B.Start_time = i;

        SELECT ADDTIME(ADDTIME(B.Start_time, P.Duration), '00:01:00') INTO @F
        FROM   Booking B, Performance P 
        WHERE  P.Code = B.Code_performance AND B.Date = Dat AND B.Id_vet = IdV AND B.Start_time BETWEEN i AND ADDTIME(i, @Duration) ORDER BY ADDTIME(B.Start_time, P.Duration) DESC LIMIT 1;

此查询没有结果。 HANDLER抓住了他们。并留下光标。

错误程序mysql db

1 个答案: