How do you check for null values in a dataset column

I have tried a large number of options to check for DBNull for a column returned in a dataset and I can't seem to figure it out. What I basically want is

Dim ds As ADMDS.PGListDataTable

Dim ta As New ADMDSTableAdapters.PGListTableAdapter

ds = ta.GetDataByPropertyGroupID(propertyGroup)

if (ds(i).prop_description is not null) then

... do something

How do I correctly check for DBNull Everything I try gives me the same error.

"The value for column 'prop_description' in table 'PGList' is DBNull."

Option 1:

l_tooltip = CType(ds(i).prop_description, SqlTypes.SqlString)

If (l_tooltip.IsNull = False) Then

Options 2:

if (ds(i).prop_description.isnullorempty = true)

Option 3:

if (ifdbnull (ds(i).prop_description) = false) then

My whole procedure list below:

Public Sub CreateColumns(ByVal l_grid As AxEXGRIDLib.AxGrid, _

ByVal propertyGroup As Integer)

Try

Dim ds As ADMDS.PGListDataTable

Dim ta As New ADMDSTableAdapters.PGListTableAdapter

Dim ds1 As ADMDS.UserColumnOrderDataTable

Dim ta1 As ADMDSTableAdapters.UserColumnOrderTableAdapter

Dim i As Integer

Dim l_tooltip As System.Data.SqlTypes.SqlString

ds = ta.GetDataByPropertyGroupID(propertyGroup)

For i = 0 To ds.Count - 1

With l_grid.Columns.Add(ds(i).prop_name)

'If Not (ds(i).prop_description.ToString = String.Empty) Then

l_tooltip = CType(ds(i).prop_description, SqlTypes.SqlString)

If (l_tooltip.IsNull = False) Then

.tooltip = l_tooltip.ToString

End If

'End If

End With

Catch ex As Exception

ShowMessage("", ex)

End Try

End Sub

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How do you check for null values in a dataset column

AlexBB
Nope.. I get the same error: Am I using isdbnull correctly below

The value for column 'prop_description' in table 'PGList' is DBNull.

ds = ta.GetDataByPropertyGroupID(propertyGroup)

For i = 0 To ds.Count - 1

With l_grid.Columns.Add(ds(i).prop_name)

If IsDBNull(ds(i).prop_description) Then

Else

'l_tooltip = CType(ds(i).prop_description, SqlTypes.SqlString)

'If (l_tooltip.IsNull = False) Then

.tooltip = ds(i).prop_description

'End If

End If

End With

Next
Rattlerr
OK - Please clarify the line and the error that you are getting, whether you have option strict on or off.

And have you actually code stepped the code to determine if the correct value is being returned from the isdbnull method

dbnull is a class not a value.
Shril Pyrrho
Are you doing this in VS05 If so, have you checked the DataSet Designer that the Column is not set to ThrowException on DBNull
gamer6000
oops, I am sorry I thought I replied to this last week.

I get the error on the line.

If ISDBnull(ds(i).prop_description) then

The error messages says : prop_description is DBNull.

Not sure that I understand the point about code stepped the isdbnull function.

Thanks

Brady
WilsonR
How about the isdbnull method to determine if it is or isnt set to dbnull.

Isdbnull Method
http://msdn2.microsoft.com/en-us/library/tckcces5.aspx
Marlon Smith

There appears to be a "feature" that prevents the DataSet Designer from changing the field to anything but ThrowException if the data type of the field is not string. The only solutions that I have found are to either bypass the strongly typed dataset property and reference the underlying column, or hack the generated code. Neither of these seem like a good long term solution. Are there any other alternatives that I am missing

Thanks
DevboyX
I only noticed this after you pointed it out. You might be better off posting a new post rather than replying to the orginal post that I posted.

Brady
stang4lyfe
Thanks for the help that was it!!!
How do you check for null values in a dataset column

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