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asp.net - checking for Null values in datatables

Posted on 2010-11-17
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Last Modified: 2012-06-27
This line is giving me, "Conversion from type 'DBNull' to type 'String' is not valid."

      strString = dt.Compute("SUM(Column1)", String.Empty)

How do I check for DBNull in a dataset?


Thank you.

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Question by:Rick
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4 Comments
 
LVL 36

Expert Comment

by:Miguel Oz
ID: 34160383
use IsDbNull method, check:
http://stackoverflow.com/questions/222834/handling-dbnull-data-in-vb-net

Note: is dt a datatable? Please provide more code
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LVL 16

Assisted Solution

by:MikeMCSD
MikeMCSD earned 200 total points
ID: 34160637

If Not Column1.GetType() Is GetType(DBNull) Then
    strString = dt.Compute("SUM(Column1)", String.Empty)
End If
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LVL 36

Assisted Solution

by:Miguel Oz
Miguel Oz earned 100 total points
ID: 34161087
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LVL 83

Accepted Solution

by:
CodeCruiser earned 1700 total points
ID: 34162579
Change this

  strString = dt.Compute("SUM(Column1)", String.Empty)

to

Dim strObj as Object =  dt.Compute("SUM(Column1)", String.Empty)
If IsDBNull(strObj) Then
   strString = 0
Else
   strString = strObj
End If
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