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how to evaluate nothing value returned by sql datareader in vb.net

Posted By:      Posted Date: August 24, 2010    Points: 0   Category :ASP.Net

When a sql query returns NULL , I can use the following code to evaluate:

While (dr.Read())
                If IsDBNull(dr(0)) Then
                End If
            End While


When a sql query returns nothing, neither IsDBNull nor is Nothing works.  I don't know why some sql queries return null while some return nothing when there are no data returned.  But anyway, can somebody tell me how to evaluate nothing value returned in sql datareader in vb.net?  When I put the cursor over signInfo variable in debug mode, I can see Nothing show as its value.  But the line does not work

if signInfo is Nothing then 


Thank you!

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