How to trap DBNull?

[cjobes]

Hi all,

I have a date field in a temp table as part of a DataSet. In some records
the value is DBNull. how can I trap the error with
if dtTemp("When") = ??? Then.....

Thanks,

Claus

 

[Lucas Tam]

Hi all,

I have a date field in a temp table as part of a DataSet. In some records
the value is DBNull. how can I trap the error with
if dtTemp("When") = ??? Then.....

If dtTemp("When") is system.dbnull.value then
Msgbox("oops dbnull!")
end if

 

[cjobes]

Thanks, that worked.

Now that the project doesn't time out anymore, I found another problem.
Where the dtTemp("When") column is not DBNull I need to replace the value of
another column (dtTemp("When2") with a value of a specific variable.
Rows.Add doesn't work (although the books say that if the PK value for the
record is already there it would replace the data) and there isn't anything
like "change" or "replace". How can I do this?

Thanks,

Claus

 

[Guest]

You Need to Edit the ItemArray associated with that row.

Also Rows.Add does work in a round about way

Dim DT As New Data.DataTable
Dim DR As Data.DataRow
DR = DT.NewRow
DR.ItemArray(0) = "Test"
DR.ItemArray(1) = "Test2"
DT.Rows.Add(DR)

Thanks, that worked.

Now that the project doesn't time out anymore, I found another problem.
Where the dtTemp("When") column is not DBNull I need to replace the value of
another column (dtTemp("When2") with a value of a specific variable.
Rows.Add doesn't work (although the books say that if the PK value for the
record is already there it would replace the data) and there isn't anything
like "change" or "replace". How can I do this?

Thanks,

Claus

 

[cjobes]

When I try this I get an error msg that the row already belongs to the
table. I also to update the item by assigning the new value to
TableX.ItemArray(3)="new value"
One column is configured as PK auto.

You Need to Edit the ItemArray associated with that row.

Also Rows.Add does work in a round about way

Dim DT As New Data.DataTable
Dim DR As Data.DataRow
DR = DT.NewRow
DR.ItemArray(0) = "Test"
DR.ItemArray(1) = "Test2"
DT.Rows.Add(DR)

 

[Cor Ligthert]

Claus,

Why would you add a row when you have to change an item in a column.
To give some explanation about items and columns.

A column is the description of a datatable column in such a column are items
Therefore
\\\
dim mycolumname as string = mytable.columns(0).columnname
///
gives you the name of the column
\\\
dim mycolumnitem as string = mytable.rows(0).item(0) or
dim mycolumnitem as string = mytable.rows(0).item(mycolumnname)
///
Gives you the first item in the first row

Therefore you need probably something as
\\\
mytable.rows(0).item(0) = myvalue
///
I hope this helps?

Cor

Thanks, that worked.

Now that the project doesn't time out anymore, I found another problem.
Where the dtTemp("When") column is not DBNull I need to replace the value
of
another column (dtTemp("When2") with a value of a specific variable.
Rows.Add doesn't work (although the books say that if the PK value for the
record is already there it would replace the data) and there isn't
anything
like "change" or "replace". How can I do this?

Thanks,

Claus

 

[Ken Tucker [MVP]]

Hi,

The datarow has an isnull method to tell if a field is dbnull.

http://msdn.microsoft.com/library/d...ml/frlrfsystemdatadatarowclassisnulltopic.asp

Ken
-----------------------
Hi all,

I have a date field in a temp table as part of a DataSet. In some records
the value is DBNull. how can I trap the error with
if dtTemp("When") = ??? Then.....

Thanks,

Claus