1. 插入数据前判断数据是否存在
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SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: <Author,,Name> -- Create date: <Create Date,,> -- Description: <Description,,> -- ============================================= alter TRIGGER CategoryExistTrigger ON ProductCategory instead of insert AS declare @categoryName varchar (50); BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON ; -- Insert statements for trigger here select @categoryName = CategoryName from inserted; if exists( select * from ProductCategory where CategoryName =@categoryName) begin print 'Category exists..' end ; else begin insert into ProductCategory select * from inserted; end ; END |
2. 删除表中数据时需要先删除外键表的数据
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SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: <Author,,Name> -- Create date: <Create Date,,> -- Description: <Description,,> -- ============================================= alter TRIGGER DeleteOrderTrigger ON OrderHeader instead of delete AS declare @OrderId varchar (50); BEGIN SET NOCOUNT ON ; select @OrderId = OrderId from deleted; delete from OrderLine where OrderId = @OrderId; END GO |