sql存储过程参数问题 [英] sql stored procedure parameter problem

问题描述

你好-
我的一个SP遇到这个奇怪的问题.
我有一个SP，参数之一是nvarchar类型.
并且我声明了该参数，我也包括了值，但是当我运行时，没有返回任何数据.
简短示例:

Hello -
I have this weird problem with one of my SP''s.
I have a SP and one of the parameters is nvarchar type.
and I am declaring the parameter, I am including value too, but when I am running there is no data returned.
short example:

@BookName nvarchar = null

然后在where子句中有:

Then in the where clause I have:

AND (o.BookName = @BookName OR @BookName IS NULL)

没有数据返回.

但是当我做的时候:

No data is returned.

But when I am doing:

AND (o.BookName = ''SQL Book'' OR @BookName IS NULL)

我得到了正确的结果.
只是让您知道该字段不是FK.

有什么想法可能是原因吗?
谢谢

I am getting the proper results.
Just to let you know that the field is no FK.

Any ideas what can be the reason?
Thanks

推荐答案

尝试:

AND (@BookName IS NULL OR o.BookName = @BookName )

有时会有所帮助

sometimes it can helps

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