SqlServer怎么实现类似Oracle的before触发器

本篇内容主要讲解"SqlServer怎么实现类似Oracle的before触发器"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"SqlServer怎么实现类似Oracle的before触发器"吧!

1. 插入数据前判断数据是否存在

SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author:  -- Create date:  -- 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

SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author:  -- Create date:  -- 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

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