SqlServer实现类似Oracle的before触发器示例

发布时间：2020-12-12 09:22:48 所属栏目：MsSql教程来源：网络整理

导读：1. 插入数据前判断数据是否存在 -- Description: -- ============================================= alter TRIGGER CategoryExistTrigger ON ProductCategory instead of insert AS declare @categoryName varchar(50); BEGIN -- SET NOCOUNT ON added to p

1. 插入数据前判断数据是否存在

-- 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 NOCOUNT ON;
select @OrderId = OrderId from deleted;
delete from OrderLine where OrderId = @OrderId;

END
GO

（编辑：李大同）

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