Question

通过SQL为这个问题的基本性质道歉，但它来自SQL noob。

我在一些在线研究后创建了以下存储过程。该过程的目的是维护计数（VisitCount），因此必须进行适当的锁定以保持完整性。据我所知MERGE为这种情况提供了正确的锁定级别，但如果有人可以建议这是否正确，我会很感激。

感谢。

ALTER PROCEDURE dbo.Popularity_Update
    @TermID int
AS
   SET NOCOUNT ON

   DECLARE @Now date = SYSDATETIME()

   BEGIN TRY
        MERGE Popularity AS t
        USING (SELECT @TermID AS TermID, @Now AS VisitDate) AS s ON t.TermID = s.TermID 
                                                                 AND t.VisitDate = s.VisitDate

        WHEN MATCHED THEN
           UPDATE 
              SET VisitCount += 1

        WHEN NOT MATCHED BY TARGET THEN
           INSERT (TermID, VisitDate, VisitCount)
           VALUES (s.TermID, s.VisitDate, 1);

     END TRY
     BEGIN CATCH
     END CATCH

Answer 1

这个怎么样....

ALTER PROCEDURE dbo.Popularity_Update
    @TermID int
AS
BEGIN
  SET NOCOUNT ON;

  DECLARE @Now date = SYSDATETIME()

    BEGIN TRY

        UPDATE Popularity
        SET VisitCount = COALESCE(VisitCount, 0) + 1
        WHERE TermID = @TermID
        AND  VisitDate = @Now

        IF (@@ROWCOUNT = 0)
        BEGIN
        INSERT INTO Popularity (TermID, VisitDate, VisitCount)
        VALUES (@TermID,  @Now, 1)
        END  

    END TRY
    BEGIN CATCH

    END CATCH 
END

正确锁定存储过程

1 个答案: