Question

我有一个在Insert上触发的触发器。此触发器插入另一个表。这是我的代码：

    SELECT @maxTeamId = 0
SELECT @maxTeamId = ISNULL(MAX(teamId), 0) from [dbo].[tblTeamslist]

--- Check if home team has already been inserted into the table.
SELECT @homeTeamId = -1
SELECT 
    @homeTeamId = teamId 
FROM 
    [dbo].[tblTeamslist] t
    JOIN inserted i
    ON t.teamName = i.hometeam
IF (@homeTeamId = -1) 
BEGIN
  SET IDENTITY_INSERT tblteamslist ON
    SELECT @homeTeamId = @maxTeamId + 1
    SELECT @maxTeamId = @maxTeamId + 1
    INSERT INTO [dbo].[tblTeamslist] (teamid,teamname) SELECT @homeTeamId, i.hometeam FROM inserted i
 SET IDENTITY_INSERT tblteamslist off
END

--- Check if away team has already been inserted into the table.
SELECT @awayTeamId = -1
SELECT 
    @awayTeamId = teamId 
FROM 
    [dbo].[tblTeamslist] t
    JOIN inserted i
    ON t.teamName = i.awayteam
IF (@awayTeamId = -1) 
BEGIN
  SET IDENTITY_INSERT tblteamslist ON
    SELECT @awayTeamId = @maxTeamId + 1
    SELECT @maxTeamId = @maxTeamId + 1
    INSERT INTO [dbo].[tblTeamslist]  (teamid,teamname) SELECT @awayTeamId, i.awayteam FROM inserted i
  SET IDENTITY_INSERT tblteamslist off
END

当你意识到我正在尝试输入一个团队，如果它在tblTeamsList上不存在。这是我得到'违反PRIMARY KEY约束'PK_tblTeamsList'的错误。无法在对象'dbo.tblTeamsList'中插入重复键。重复键值为（24）。'。在代码中我试图每次增加id +1。出了什么问题？

Answer 1

有两种情况可能会发生此错误。 1）如果在单个insert语句中插入多行，则触发器仅触发一次。在这种情况下插入（如Chris所述）将包含多行。现在插入到tblTeamList中也会尝试插入多行 - 所有这些行都具有相同的teamid。

2）如果这些插入中的两个同时发生，则它们都可能读取相同的@maxTeamId。如果发生这种情况，他们都会尝试使用相同的teamid将记录插入到tblTeamList中。

要防止这两个问题，请使用表格上的标识功能，而不是尝试绕过它。

触发器正在尝试插入重复键

1 个答案: