從WHERE子查詢SQL Server更新

Question

如何使用UPDATE語句中的子查詢？ 這是我的查詢：

UPDATE car_availability
SET    availability_status = 'GOOD'
FROM   car_trip AS TRIP
WHERE  car_availability.car_no = TRIP.car_no 
AND NOT EXISTS (SELECT DISTINCT A.car_No 
                FROM   car_maintenance A 
                WHERE  A.car_no = TRIP.vehicle_id 
                AND    start_date = TRIP.workday)
AND EXISTS (SELECT DISTINCT B.car_No 
            FROM   car_maintenance B 
            WHERE  B.car_no = TRIP.vehicle_id 
            AND end_date IS NOT NULL)

我收到錯誤消息“ UPDATE和DELETE語句中的FROM子句不能包含子查詢源或聯接。”

我想將Availability_Status更新為GOOD，其中car_maintenance中存在的汽車的start_date等於car_trip的工作日，而car_maintenance中的汽車的結束日期不為空。

Answer 1

正如@McNets所說，您需要將car_availability表添加到FROM子句中。 嘗試這個：

UPDATE CA
SET    availability_status = 'GOOD'
FROM   car_availability CA
JOIN car_trip AS TRIP ON CA.car_no = TRIP.car_no 
WHERE NOT EXISTS (SELECT DISTINCT A.car_No 
                FROM   car_maintenance A 
                WHERE  A.car_no = TRIP.vehicle_id 
                AND    start_date = TRIP.workday)
AND EXISTS (SELECT DISTINCT B.car_No 
            FROM   car_maintenance B 
            WHERE  B.car_no = TRIP.vehicle_id 
            AND end_date IS NOT NULL)