存储过程的正确锁定

Question

SQL对此问题的基本性质表示歉意，但它来自SQL noob。

我在一些在线研究后创建了以下存储过程。该过程的目的是维持计数（VisitCount），因此需要适当的锁定以保持完整性。据我所知MERGE给出了这种情况下正确的锁定水平，但我会很感激，如果有人可以建议这是否正确与否。

谢谢。

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