For a form that has two DataGridView controls, I find following piece of
code (free of bindingsource, binding navigator, typed dataset etc
enhancements) conceptually a simple and effective way to display
parent-child relationship. The two grids are synchronized (selecting record
in the parent grid updates records in the child grid) and everything works
ok.

But the problem is that this code only works when I place it in the form
constructor. Any attempt to locate this code in the form load event or a
button click event results in a blank child grid (0 child records in
DataGridView2). This is strange as I fail to see any line in my code that
should/can only appear in constructor. Please guide me on this problem.

Thanks
Mansoor

Code that only works OK in form constructor:
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           DataSet dataSet;

           SqlConnection objConnection;
           SqlDataAdapter objDataAdapter;

           DataColumn parentColumn;
           DataColumn childColumn;

           //Open connection
           objConnection = new SqlConnection(connectionString);
           objConnection.Open();

           //Initialize dataset
           dataSet = new DataSet("NorthWindDataset");

           //Create and fill Customers datatable
           objDataAdapter = new SqlDataAdapter("SELECT * FROM Customers",
objConnection);
           objDataAdapter.Fill(dataSet, "Customers");

           //Create and fill Orders datatable
           objDataAdapter = new SqlDataAdapter("SELECT * FROM Orders",
objConnection);
           objDataAdapter.Fill(dataSet, "Orders");

           //Close connection
           objConnection.Close();

           //Create foreign key constraint and relationship between
Customers and Orders datatable
           parentColumn =
dataSet.Tables["Customers"].Columns["CustomerID"];
           childColumn = dataSet.Tables["Orders"].Columns["CustomerID"];
           dataSet.Relations.Add("Customer_Orders", parentColumn,
childColumn);

           //Bind grid to parent records
           dataGridView1.DataMember = "Customers";
           dataGridView1.DataSource = dataSet;

           //Bind grid to child records
           dataGridView2.DataMember = "Customers.Customer_Orders";
           dataGridView2.DataSource = dataSet;