INSERT SELECT MIN(COUNT) 插入 ID 后触发

Question

我正在尝试在 eventss 表上插入后创建触发器。触发器应从bookingCoordinator 表中选择Bcoordinator_ID，它们在eventss 表中的出现次数最少。

这是我的表数据，后面是触发器。它不喜欢值中的minCount，我认为它正在寻找和int。

DROP TABLE eventsBooking
CREATE TABLE eventsBooking 
(
      EBK INT NOT NULL IDENTITY(100, 1),
      booking_ID AS 'EBK'+CAST( ebk as varchar(10)) PERSISTED PRIMARY KEY,

      bookingDate DATE,
      Bcoordinator_ID VARCHAR (20),
      eventss_ID VARCHAR (20) NOT NULL
)

INSERT INTO eventsBooking    
VALUES ('2015-01-07 11:23:00', NULL, 'EVT100');

Eventss表：

EVT INT NOT NULL IDENTITY(100, 1),
eventss_ID AS 'EVT' + CAST(evt as varchar(10)) PERSISTED PRIMARY KEY,

eventsName varchar(50), 
noOfStages SMALLINT, 
noOfRounds SMALLINT, 
eventsDate DATE,
entryFee DECIMAL (7,2),
venue_ID VARCHAR (20) NOT NULL,
judges_ID VARCHAR (20)

INSERT INTO eventss  
VALUES ('Swimming Gala 2015', '3', '7', '2015-01-07 09:00:00', '35.00', 'VEN101', 'JUD100');



CREATE TABLE bookingCoordinator 
(
      BCO INT NOT NULL IDENTITY(100, 1),
      Bcoordinator_ID AS 'BCO'+CAST( bco as varchar(10)) PERSISTED PRIMARY KEY,

      forename varchar(20) NOT NULL, 
      familyName varchar(50)
)

INSERT INTO bookingCoordinator VALUES ('Steve', 'Wills');

触发器：

CREATE TRIGGER TRGinsertJudge 
ON  [dbo].[eventss]
AFTER INSERT 
AS 
BEGIN
   SET NOCOUNT ON;

   INSERT INTO dbo.eventsBooking (Bcoordinator_ID, bookingDate, Eventss_ID)             
   VALUES(minCount, getdate(), 100)

   SELECT MIN(COUNT(Bcoordinator_ID)) AS minCount
   FROM eventsBooking
END

Answer 1

您不能对聚合进行聚合，即MIN(COUNT(1))

如果您只想要 eventsBooking 中计数最少的 Bcoordinatior_ID，请执行此操作

select top 1 bcoordinator_id 
from eventsBooking 
group by bcoordinator_id 
order by count(1) asc

而且您不会在 INSERT INTO ... SELECT 语句中使用 VALUES()

另外，在您当前的代码中，由于 eventsBooking.bcoordinator_id 始终为空，您需要加入实际的 bookingCoordinators 表以返回未预订任何活动的预订协调员。

所以你完整的触发语句应该是

    INSERT INTO dbo.eventsBooking (Bcoordinator_ID, bookingDate, Eventss_ID)                
     select 
 top 1
  bookingcoordinator.bcoordinator_id, getdate(), 100 
    from bookingCoordinator left join eventsBooking 
        on bookingCoordinator.Bcoordinator_ID = eventsBooking.Bcoordinator_ID
    group by bookingcoordinator.bcoordinator_id 
    order by count(1) asc