"Hexman" wrote:

> Hello all,
>
> Back again with more questions.  I have a task at hand and I'm trying
> to use a datarelation between two datatables. 
>
> Table1 = Trans
> fields= date, product, dept, assignto, .....
>
> 04/01/06 Clamp       54    <blank>
> 04/01/06 Valve        55   <blank>
> 04/01/06 Body         54   <blank>
>
> Table2 = Staff
> fields= dept, person, .....
>
> 54 Alice
> 54 Tom
> 55 Bob
> 55 Mary
> 55 Robert
>
> I've set up 2 datagrids with each of the tables attached, now I want
> to relate the Trans table to the Staff table using the dept as the
> related columns.  Here's my code.
>
>         Dim data_relation As New DataRelation("Trans-Staff", _
>            ds.Tables("Trans").Columns("TRDept"), _
>            ds.Tables("Staff").Columns("STDept"))
>         ds.Relations.Add(data_relation)
>
> When I go to execute, it fails on the ds.relations.add line and comes
> up with this error.
> ---------------------------------
> An unhandled exception of type 'System.ArgumentException' occurred in
> system.data.dll
>
> Additional information: These columns don't currently have unique
> values.   
> ---------------------------------
>
> The objective is to show all Trans in grid 1, and as a row is
> selected, show only the Staff for the department that is selected in
> grid 1.  From there, one row of the staff will be selected (being
> assigned to that transaction).  I then plan to update the Staff row
> with some info and update the trans with the person assigned from the
> Staff table and other information.
>
> I'm sure this has been done before.  Any full examples would be
> appreciated, but right now I need to fix this datarelation problem.
>
>
> Thanks,
>
> Hexman
>
>
>

>Hi,
>Are your datacolumn names "dept", or are they "TRDept" and "STDept"?  If
>actually "dept", then
>
>Dim data_relation As New DataRelation("Trans-Staff", _
>>            ds.Tables("Trans").Columns("dept"), _
>>            ds.Tables("Staff").Columns("dept"))
>>         ds.Relations.Add(data_relation)
>
>You will get an ArgumentNullException from the constructor if one or both of
>the DataColumn objects contains a null reference.
>
>JT

> JT,
>
> The actual names of the fields are "TRDept" & "STDept".  Both are
> defined as text fields with a length of 3.
>
> Hexman
>
>
> On Wed, 19 Apr 2006 18:49:03 -0700, JT <Jthayer@online.nospam> wrote:
>
> >Hi,
> >Are your datacolumn names "dept", or are they "TRDept" and "STDept"?  If
> >actually "dept", then
> >
> >Dim data_relation As New DataRelation("Trans-Staff", _
> >>            ds.Tables("Trans").Columns("dept"), _
> >>            ds.Tables("Staff").Columns("dept"))
> >>         ds.Relations.Add(data_relation)
> >
> >You will get an ArgumentNullException from the constructor if one or both of
> >the DataColumn objects contains a null reference.
> >
> >JT
>