Multiple tables in data relations

Windows Forms Data Controls and Databinding

Chris1973

Hi

My code

DataSet ds = new DataSet();

//Get the customers data

SqlCommand cmdCustomers = conn.CreateCommand();

cmdCustomers.CommandType = CommandType.Text;

cmdCustomers.CommandText = "Select * FROM Customers";

SqlDataAdapter daCustomers = new SqlDataAdapter();

daCustomers.SelectCommand = cmdCustomers;

daCustomers.Fill(ds, "Customers");

//Get the orders data

SqlCommand cmdOrders = conn.CreateCommand();

cmdOrders.CommandType = CommandType.Text;

cmdOrders.CommandText = "Select * FROM Orders";

SqlDataAdapter daOrders = new SqlDataAdapter();

daOrders.SelectCommand = cmdOrders;

daOrders.Fill(ds, "Orders");

//Get the order details data

SqlCommand cmdOrderDetails = conn.CreateCommand();

cmdOrderDetails.CommandType = CommandType.Text;

cmdOrderDetails.CommandText = "Select * FROM [Order Details]";

SqlDataAdapter daOrderDetails = new SqlDataAdapter();

daOrderDetails.SelectCommand = cmdCustomers;

daOrderDetails.Fill(ds, "[Order Details]");

//Add the relations

DataRelation drCustOrder = ds.Relations.Add("CustOrders",

ds.Tables["Customers"].Columns["CustomerID"],

ds.Tables["Orders"].Columns["CustomerID"]);

DataRelation drOrderDetails = ds.Relations.Add("OrderDetails",

ds.Tables["Orders"].Columns["OrderID"],

ds.Tables["Order Details"].Columns["OrderID"]);

//Show the data

masterDatagridView.DataSource = ds;

masterDatagridView.DataMember = "Customers";

geneates the following error for the second data relation, OrderDetails:

"Object reference not set to an instance of an object"

I would like to be able to show Customers, Orders, and Order details on a datagridview, allowing the user to drill down to the lowest level, by expanding the nodes on the grid

The code works fine if the second data relation is removed

Thanks

Chris1973
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Re: Windows Forms Data Controls and Databinding Multiple tables in data relations

Zhi-Xin Ye - MSFT

Chris1973 wrote:

SqlDataAdapter daOrderDetails = new SqlDataAdapter();

daOrderDetails.SelectCommand = cmdCustomers;

daOrderDetails.Fill(ds, "[Order Details]");

DataRelation drOrderDetails = ds.Relations.Add("OrderDetails",

ds.Tables["Orders"].Columns["OrderID"],

ds.Tables["Order Details"].Columns["OrderID"]);



The table name you used are not the same, the preceding one has brackets, the other one not. That's the problem.





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