存储过程删除查询

Question

我有存储过程:

ALTER PROCEDURE [dbo].[k_ShoppingCart_DELETE]

@cartGUID nvarchar

AS

DELETE FROM
  [dbo].[k_ShoppingCart]
WHERE
  CartGUID = @cartGUID

当我执行这个时,

exec dbo.k_ShoppingCart_DELETE '32390b5b-a35a-4e32-8393-67d5629192f0'

结果:0行受影响.

但是,当我尝试这个查询时:

Delete FROM k_ShoppingCart Where CartGUID = '32390b5b-a35a-4e32-8393-67d5629192f0'

结果:2行受影响.

这有什么问题？

Answer 1

如果您坚持使用 NVARCHAR 而不是 UNIQUEIDENTIFIER，则需要指定大小：

@cartGUID nvarchar(36)

如果没有它，您的 guid 将被截断（至 30 个字符）。

您可以通过运行工作查询的修改版本来确认此行为：

DECLARE @cart nvarchar, @sizedcart nvarchar(36)
SET @cart      = '32390b5b-a35a-4e32-8393-67d5629192f0'
SET @sizedcart = '32390b5b-a35a-4e32-8393-67d5629192f0'

-- works
Delete FROM k_ShoppingCart Where CartGUID = '32390b5b-a35a-4e32-8393-67d5629192f0'

-- will not work
Delete FROM k_ShoppingCart Where CartGUID = @cart

-- should work
Delete FROM k_ShoppingCart Where CartGUID = @sizedcart

不过，我同意@Marc Gravell 的观点，uniqueidentifier 是解决问题的方法。