Regarding null values in the database

Posted Date: 06 Oct 2008 Posted By: Hamar Kharshiing Member Level: Gold Points: 1 Responses: 3

Hi,

Im having a to_user field in the table as null..
In my code i am checking it like this using tableadapter.
Dim ta As DataSet1TableAdapters.messageTableAdapter = New DataSet1TableAdapters.messageTableAdapter
Dim dt As DataSet1.messageDataTable = ta.GetMessagesbyroomid(Request("RoomID"))

If Not dt Is Nothing Then

For Each message As DataSet1.messageRow In dt
if message.to_user is nothing then
'do something
end if
next
End if

That means if in one of the rows using for each loop, the to_user field is null then we do something. But it is giving me this error:
"The value for column 'to_user' in table 'message' is DBNull."

StrongTypingException was unhandled by user code..
Hellp me on this..plz..

regards,
Hamar

Responses

Author: Anil Kumar Pandey 06 Oct 2008

Member Level: Diamond

Rating:

Points: 2

hi,

try this

For Each message As DataSet1.messageRow In dt
ifconvert.Tostring(message.to_user)=="" then
'do something
end if
next
End if

Regards
Anil

Thanks & Regards
Anil Kumar Pandey

Author: Hamar Kharshiing 06 Oct 2008

Member Level: Gold

Rating:

Points: 1

Hi Anil,

It is still givin the same error.

Author: Vivek 10 Oct 2008

Member Level: Gold

Rating:

Points: 2

You need to use DBNulll to check database null values.

first retrieve DataSet values in DataRow

then check

If Not IsDBNull(stringValue) Then

// Your Code
End If

http://msdn.microsoft.com/en-us/library/tckcces5.aspx
http://www.thedatafarm.com/blog/2005/09/09/NullableTypeAndDbNull.aspx

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