if条件失败的存储过程

Question

我正在使用mysql中的if else条件创建存储过程。如果条件有效，则程序运行良好但如果我放条件则失败。它甚至没有显示语法错误。

CREATE PROCEDURE inputCars()
    BEGIN
        DECLARE n INT DEFAULT 0;
        DECLARE i INT DEFAULT 0;
        DECLARE j INT DEFAULT 0;
        DECLARE d INT DEFAULT 0;
        SELECT count(*)
        FROM devtakci.tb_users AS a INNER JOIN devtakci.tb_driver_details AS b ON a.user_id = b.driver_id
        WHERE a.status = 0 AND a.reg_as = 1
        INTO n;
        SET i = 0;
        SET j = 0;
        WHILE (i < n) DO
            IF EXISTS(SELECT driver_id
                      FROM adapter.tb_available_cars
                      WHERE driver_id = (SELECT user_id
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1))
            THEN
                UPDATE adapter.tb_available_cars
                SET
                    vehicle_type      = (SELECT car_type
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    driver_phone      = (SELECT phone_no
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    vehicle_plate     = (SELECT driver_car_no
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    latitude          = (SELECT current_location_latitude
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    longitude         = (SELECT current_location_longitude
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    direction_heading = (SELECT driver_car_direction_angle
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    status            = (SELECT status
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1),
                    driver_id         = (SELECT user_id
                                         FROM devtakci.tb_users
                                         ORDER BY user_id ASC
                                         LIMIT i, 1)
                WHERE driver_id = (SELECT user_id
                                   FROM devtakci.tb_users
                                   ORDER BY user_id ASC
                                   LIMIT i, 1)
            ELSE
                INSERT INTO adapter.tb_available_cars (vehicle_type, driver_phone, vehicle_plate, latitude, longitude, direction_heading, status, driver_id, make, model, driver_first_name, driver_last_name)
                    SELECT
                        a.car_type,
                        a.phone_no,
                        a.driver_car_no,
                        a.current_location_latitude,
                        a.current_location_longitude,
                        a.driver_car_direction_angle,
                        a.status,
                        b.driver_id,
                        b.vehicle_make,
                        b.vehicle_model,
                        b.first_name,
                        b.last_name

                    FROM devtakci.tb_users AS a
                        INNER JOIN devtakci.tb_driver_details AS b ON a.user_id = b.driver_id
                    WHERE a.status = 0 AND a.reg_as = 1

                    ORDER BY a.user_id ASC
                    LIMIT i, 1;
            END IF;
            SET i = i + 1;
        END WHILE;
    END;

如果我执行它，如果条件有效则跳过，但是当我把IF ELSE子句

时失败

Answer 1

在mysql中，您只能在查询中使用exists，而不能在compund语句本身中使用insert ... on duplicate key update ...。您需要将driver_id提取到变量中，if可以根据变量的值来设置decidion。

但整个if语句似乎是QString statemen5的复杂形式。