DataGrid and DataSet information

[Sébastien]

Hi,

I have 2 parents tables (example : Car and Road). That Car can use n
Roads and Road can be use by n Cars. In that case, I need a middle table
because it is a n-to-n relation. So we had a Link_Car_Road table with the
primary key of Road and Car as foreign key in Link_Car_Road.

So if I want to design a form to show the car informations with all the road
corresponding to that car, I need to use a DataGrid (I think, because it
seems impossible with a ListBox). I am able to show the car ifnromations
with the Link_Car_Road information, but I am unable to get the Road with my
DataGrid. To do it, I set the DataSource of my DataGrid to my DataSet and my
CalueMember to Car.Link_Car_Road_Relation. So when I select a new car
record, I get all the child rows of Link_Car_Road that correspond to that
car. IS there any way to get the Road information instead the middle table
informations when I select a new car row ?

Thank you for your help.

 

[William Ryan [eMVP]]

Sebastien:

I think binding to a DataView and adjusting the rowfilter is a decent way to
get there. Say the Road grid is bound to the row filter and you change car.
You can then reset the rowfilter of the Link_Car_Road table (which should
only have ostensibly one record if I understand the schema correctly. From
there, the .RowFilter for the Road View could be set to the value in
Link_Car_Road. Once the Rowfilter is set to the correct value, the correct
records will show in the Road grid immediately.

 

[Sébastien]

The Link_Car_Road table will have multiple record of the same car or Road.
Example :

I have Car 1, 2 and 3
I have Road 11, 12 and 13

My table could look like

1 11
2 11
1 13
1 12
3 11
2 13
3 13

So if I understand you solution, It will work inly with one record.

I think I could use the GetParentRows method, but I am not sure we can use
DataBinding with that.

Thank you for your help.

 

[William Ryan [eMVP]]

Ok, but the solution will still work. All you'll need to do is loop through
the filtererd rows on of the dataview and construct a RowFilter expression
based on multiple criteria:

So lets say that originally you wanted to set it so RowFilter = "Road_ID =
'1' assuming you go 1 as a filtered value. Instead, now you might have 5
different values. You could change it so RowFilter = "Road_ID IN ('1', '2',
'3', '4','5').

Here's a sample of a proc I wrote to walk through a DataTable and extract
duplicate values...from there, I build an IN Expression so I can set my
rowfilter to only show values that are duplicates.

Public Sub ShowOnlyDuplicates(ByVal Dups As ArrayList)

If Dups.Count = 0 Then

MessageBox.Show("There doesn't appear to be any duplicate records", "No
Duplicates Found", MessageBoxButtons.OK, MessageBoxIcon.Information)

Exit Sub

End If

Dim sb As New System.Text.StringBuilder

sb.Append(FieldName & " IN( ")

For i As Integer = 0 To Dups.Count - 1

If i = 0 Then

sb.Append("'" & CType(Dups(i), String) & "'")

Else

sb.Append(", '" & CType(Dups(i), String) & "'")

End If

Next

sb.Append(")")

GridSource.RowFilter = sb.ToString

GridSource.Sort = "Excel_Job_Number"

End Sub



HTH,



Bill