more than one column in a datarelation

Hello,

All the samples I got only has 1 column that relates 2 tables.

Dim MyDataRelation As DataRelation
MyDataRelation = New DataRelation("BrUserDept", dtBranchUser.Columns("userid"), dtBranchDept.Columns("userid"))
dsUserDept.Relations.Add(MyDataRelation)

How will I relate 2 tables using more than one column?

Thanks in advance.

Got it!

VB Code:

Sub CreateDataSet()
 
        Dim MyConnection As New SqlConnection()
        MyConnection.ConnectionString = ConfigurationSettings.AppSettings("OpalConnect")
        Try
 
            Dim strSQL As String = "SELECT userid, branchcode, def FROM BranchUser"
            Dim scmd As New SqlCommand(strSQL, MyConnection)
            sda = New SqlDataAdapter(scmd)
            Dim scb As New SqlCommandBuilder(sda)
            scb.GetUpdateCommand()
 
            ' Create a new DataSet and fill its first DataTable.
            dsUserDept = New DataSet()
            sda.Fill(dsUserDept, "BranchUser")
 
            ' Reset the CommandText to get the User dept
            scmd.CommandText = "select userid, branchcode, deptcode, def from BranchDept"
 
            ' Fill the second table in the DataSet.
            sda.Fill(dsUserDept, "BranchDept")
 
            ' Set variables for the DataTables for use later.
            dtBranchUser = dsUserDept.Tables(0)
            dtBranchDept = dsUserDept.Tables(1)
 
            ' Set up DataViews for the DataGrids 
            dvBranchUser = dtBranchUser.DefaultView
            dvBranchDept = dtBranchDept.DefaultView
 
            Dim MyDataRelation As DataRelation
            Dim ParentCols() As DataColumn
            Dim ChildCols() As DataColumn
 
            ParentCols(0) = dtBranchUser.Columns("userid")
            ParentCols(1) = dtBranchUser.Columns("branchcode")
 
            ChildCols(0) = dtBranchDept.Columns("userid")
            ChildCols(1) = dtBranchDept.Columns("branchcode")
 
            MyDataRelation = New DataRelation("BrUserDept", ParentCols, ChildCols)
 
            dsUserDept.Relations.Add(MyDataRelation)
    
End Sub

But I got an error message when I run it:

Object reference not set to an instance of an object

What could be wrong?

Thanks in advance.

Its because of the way you declared the array of columns. You can not say for example:

Dim X() as Integer
X(0)=10

I think that's because 'Dim x() as Integer' does not allocate memory for x(). You have to redim.