mysql - UPDATE FROM WHERE 子查询 SQL Server

Question

如何使用 UPDATE 语句中的子查询？这是我的查询:

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)

我收到错误“UPDATE 和 DELETE 语句中的 FROM 子句不能包含子查询源或联接。”

我想将availability_status更新为GOOD，其中car_maintenance中存在的汽车其开始日期等于car_trip的工作日，并且car_maintenance中的汽车其结束日期不为空。

Answer 1

正如 @McNets 所说，您需要将 car_availability 表添加到 FROM 子句中。试试这个:

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)