处理触发器中的多行（BULK 插入）答案

【问题标题】：Handle multiple rows in trigger (BULK insert)处理触发器中的多行（BULK 插入）
【发布时间】：2013-07-28 00:41:05
【问题描述】：

我做了一个批量插入，我有一个触发器，它会相应地进行一些检查和插入：假设我的批量插入有两列 HomeTeam AwayTeam。

HomeTeam     AwayTeam
Team1         Team3
Team6         Team9
Team3         Team5

我的数据库有两个表，tblTeamsList(Id,TeamName) 包含团队和 tblPremierLeague(id,HomeTeam,AwayTeam)，我执行批量插入。我有一个 INSTEAD OF INSERT 触发器，它检查 HomeTeam 是否在 tblTeamsList 中，如果没有，则将其插入 tblteams 中，然后检查 AwayTeam 并执行相同操作。最后我想用他们的外键而不是名字将它们插入 tblPremierleague。这是我的触发器。

   instead of INSERT
AS
BEGIN
    DECLARE @homeTeamId INT
    DECLARE @awayTeamId INT
    DECLARE @maxTeamId INT
    DECLARE @matchId INT
    DECLARE @home nvarchar(100)
    DECLARE @away nvarchar(100)

    DECLARE cur CURSOR FOR
    Select HomeTeam,AwayTeam from inserted
    OPEN cur
    FETCH NEXT FROM cur INTO @home, @away

    --- 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 = @home
    IF (@homeTeamId = -1) 
    BEGIN

        INSERT INTO [dbo].[tblTeamslist] (teamname) SELECT  i.hometeam FROM inserted i

    END

    --- Check if away team has already been inserted into the table.
     SELECT @maxTeamId = 0
    SELECT @maxTeamId = ISNULL(MAX(teamId), 0) from [dbo].[tblTeamslist]


    SELECT @awayTeamId = -1
    SELECT 
        @awayTeamId = teamId 
    FROM 
        [dbo].[tblTeamslist] t
        JOIN inserted i
        ON t.teamName = @away
    IF (@awayTeamId = -1) 
    BEGIN

        INSERT INTO [dbo].[tblTeamslist]  (teamname) SELECT  i.awayteam FROM inserted i

    END

    -- insert a record into the matches table with the home team ID and away team ID.

    INSERT INTO [dbo].[tblpremierLeague] 
    SELECT  @homeTeamId, @awayTeamId
    FROM inserted i
FETCH NEXT FROM cur INTO @home, @away

    END
    CLOSE cur
    DEALLOCATE cur

上述触发器无法正常工作，我在 tblPremierLeague 中获得了 300 行相同的行，所有行的值都相同，如下所示：

HomeTeam        AwayTeam
 -1                1

awayteamId 是正确的。而且在 tblTeamsList 中多次插入同一个团队。任何帮助如何纠正我的触发器？

【问题讨论】：

标签： sql sql-server tsql

【解决方案1】：

假设 id 是 IDENTITY 列：

-- Add all of the home teams we haven't heard of before.
insert into dbo.tblTeamsList
  select i.HomeTeam
    from inserted as i left outer join
      tblTeamsList as TL on TL.TeamName = i.HomeName
    where TL.Id is NULL

-- Add all of the alien teams we haven't heard of before.
insert into dbo.tblTeamsList
  select i.AwayTeam
    from inserted as i left outer join
      tblTeamsList as TL on TL.TeamName = i.AwayTeam
    where TL.Id is NULL

-- Add any **new** pairs to the league.
insert into tblPremierLeague
  select H.Id, A.Id
    from inserted as i inner join
      tblTeamsList as H on H.TeamName = i.HomeTeam inner join
      tblTeamsList as A on A.TeamName = i.AwayTeam left outer join
      tblPremierLeague as TL on TL.HomeTeam = H.Id and TL.AwayTeam = A.Id
    where TL.Id is NULL

请不要通过 Agonizing Row (RBAR) 来执行此行。使用集合操作。

而且很多人并不关心命名表tblMumble 的人造匈牙利符号。我会使用Mumbles。

【讨论】：