Question

我有一个触发器，它根据INSERTED的一个值插入到另一个表中。

CREATE TRIGGER 
    [dbo].[triggerTest]
ON 
    [dbo].[Original]
AFTER INSERT
AS
  BEGIN
    SET NOCOUNT ON

      If (SELECT city FROM INSERTED) = 'LA' 
          INSERT INTO Hotel 
          SELECT price, quality FROM Inserted AS I
      ELSE IF (SELECT city FROM INSERTED) = 'NY'
          INSERT INTO Inn
          SELECT price, quality FROM Inserted AS I
END

我发现当我在Original表中插入多行时，出现此错误：

SQL Server子查询返回了多个值。当子查询遵循=，！=，<，<=，>，> =
时，不允许这样做

上述触发器有什么问题？

Answer 1

您的INSERTED表返回了更多的行，因此，您需要top (1)和order by子句，但我会改为exists：

CREATE TRIGGER [dbo].[triggerTest]
ON  [dbo].[Original]
AFTER INSERT
AS
  BEGIN
    SET NOCOUNT ON

      IF EXISTS (SELECT 1 FROM INSERTED WHERE city = 'LA')
          INSERT INTO Hotel (price, quality)
               SELECT price, quality 
               FROM Inserted AS I
      IF EXISTS (SELECT 1 FROM INSERTED WHERE city = 'NY')
          INSERT INTO Inn (price, quality)
               SELECT price, quality 
               FROM Inserted AS I
  END

注意：

在执行INSERT操作时始终显式限定列名。

Sql Server触发器错误：SqlException：子查询返回了多个值。

1 个答案: