null参数问题 [英] Problem with null parameter
问题描述
嗨
我有一个带有以下SQL的datadapter;
SELECT ID，公司，状态，公司类型
FROM Companies
WHERE（@Status IS NULL或@Status = Status）
当我尝试这样填充时;
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，" Current"），它带来所有
公司的状态为Current。
问题是，当我使用
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，DBNull.Value.tostring）来填充
带来所有公司无论身份如何，那么而不是得到所有
公司我什么也得不到。我怎样才能解决这个问题？
谢谢
问候
Hi
I have a datadapter with the following SQL;
SELECT ID, Company, Status, CompanyType
FROM Companies
WHERE (@Status IS NULL or @Status = Status)
When I try to fill like so;
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, "Current"), it brings all
companies with status Current.
The problem is that when I fill using
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, DBNull.Value.tostring) to
bring all companies regardless of status, then instead of getting all
companies I get nothing. How can I get this fixed?
Thanks
Regards
推荐答案
John< Jo ** @ nospam.infovis.co.uk>写道：
John <Jo**@nospam.infovis.co.uk> wrote:
我有一个带有以下SQL的datadapter;
SELECT ID，公司，状态，公司类型
FROM Companies
WHERE（@Status IS NULL或@Status =状态）
当我尝试像这样填充;
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，Current），它带来所有
状态为Current的公司。
问题是，当我使用
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，DBNull.Value.tostring）填写
时无论身份如何，所有公司都会被带到公司，而不是让所有的公司都得到我的一切。我怎样才能解决这个问题？
I have a datadapter with the following SQL;
SELECT ID, Company, Status, CompanyType
FROM Companies
WHERE (@Status IS NULL or @Status = Status)
When I try to fill like so;
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, "Current"), it brings all
companies with status Current.
The problem is that when I fill using
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, DBNull.Value.tostring) to
bring all companies regardless of status, then instead of getting all
companies I get nothing. How can I get this fixed?
嗯，这正是你所要求的。当@Status为null时，
你的WHERE子句是：
WHERE（NULL是NULL或NULL =状态）
现在，第二个条款显然从来都不是 - 但第一个是
*总是*真！
我*怀疑*你的意思是：
WHERE（@Status IS为空且状态为空）或（@状态=状态）
-
Jon Skeet - < sk *** @ pobox.com>
http：// www .pobox.com / ~silet 博客： http：//www.msmvps .com / jon.skeet
如果回复小组，请不要给我发邮件
Well, it''s doing exactly what you''ve asked it to. When @Status is null,
your WHERE clause is:
WHERE (NULL IS NULL OR NULL = Status)
Now, the second clause is obviously never true - but the first one is
*always* true!
I *suspect* you meant:
WHERE (@Status IS NULL AND Status IS NULL) OR (@Status=Status)
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
我*是*正在寻找子句WHERE（NULL IS NULL或NULL = Status）以便
为@status发送空值并带回所有
记录。问题是它没有返回！
谢谢
问候
" Jon Skeet [ C＃MVP]" < SK *** @ pobox.com>在消息中写道
新闻：MP *********************** @ msnews.microsoft.co m ...
I *am* looking for the clause WHERE (NULL IS NULL OR NULL = Status) so that
it is true for when null value is sent for @status and brings back all
records. Problem is it is returning none!
Thanks
Regards
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP***********************@msnews.microsoft.co m...
John< Jo ** @ nospam.infovis.co.uk>写道：
John <Jo**@nospam.infovis.co.uk> wrote:
我有一个带有以下SQL的datadapter;
SELECT ID，公司，状态，公司类型
FROM Companies
WHERE（@Status IS NULL或@Status =状态）
当我尝试填充时;
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，Current），它带来了
所有
公司状态为Current。
问题是，当我填写使用
Me.CompanyTableAdapter.Fill（Me.MyDataSet.Clients，DBNull.Value.tostring）<无论身份如何，所有公司都会被带到所有公司，而不是得到所有公司，我什么也得不到。我怎样才能解决这个问题？
I have a datadapter with the following SQL;
SELECT ID, Company, Status, CompanyType
FROM Companies
WHERE (@Status IS NULL or @Status = Status)
When I try to fill like so;
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, "Current"), it brings
all
companies with status Current.
The problem is that when I fill using
Me.CompanyTableAdapter.Fill(Me.MyDataSet.Clients, DBNull.Value.tostring)
to
bring all companies regardless of status, then instead of getting all
companies I get nothing. How can I get this fixed?
好吧，它正在按照你的要求去做。当@Status为null时，你的WHERE子句是：
WHERE（NULL是NULL或NULL =状态）
现在，第二个子句显然永远不会是真的 - 但第一个是
*总是*真的！
我*怀疑*你的意思是：
WHERE（@Status IS NULL和Status IS NULL）或者（@状态=状态）
- Jon Skeet - < sk *** @ pobox.com>
http://www.pobox.com/~skeet 博客： http://www.msmvps.com/jon.skeet
如果回复该群组，请不要给我发邮件
Well, it''s doing exactly what you''ve asked it to. When @Status is null,
your WHERE clause is:
WHERE (NULL IS NULL OR NULL = Status)
Now, the second clause is obviously never true - but the first one is
*always* true!
I *suspect* you meant:
WHERE (@Status IS NULL AND Status IS NULL) OR (@Status=Status)
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
John< Jo ** @ nospam.infovis.co.uk>写道：
John <Jo**@nospam.infovis.co.uk> wrote:
我*正在寻找WHERE（NULL IS NULL或NULL = Status）子句，以便当为@status发送空值并将所有值带回时，它是真的
记录。问题是它没有返回！
I *am* looking for the clause WHERE (NULL IS NULL OR NULL = Status) so that
it is true for when null value is sent for @status and brings back all
records. Problem is it is returning none!
我道歉 - 我误读了你以前的帖子。
嗯 - 你放了吗SQL Server上的探查器，用于检查查询中实际提交的值是多少？
？恐怕我现在不能轻易测试一下这个价格。
-
Jon Skeet - < sk *** @ pobox.com>
http：// www .pobox.com / ~silet 博客： http：//www.msmvps .com / jon.skeet
如果回复小组，请不要给我发邮件
I do apologise - I misread your previous post.
Hmm - have you put a profiler onto SQL Server to check what value is
actually being submitted in the query? I''m afraid I can''t easily test
it myself at the moment.
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
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