SqlServer实现类似Oracle的before触发器示例

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: Author,,Name -- Create date: Create Date,, -- Description: Description,, -- ============

                       <p>1. 插入数据前判断数据是否存在</p>

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