Not sure whether you mean DataTable or Dataset. If you execute the following query:
select customer.customerid, customername, orderid, orderdate, orderamount
from customer inner join orders
on customer.customerid = orders.customerid and customer.customerid = {your id here passed as a parameter}
via a Command object, the results can be placed in a DataTable. If you execute the following two queries in one command, the result can be placed in a DataSet for client-side processing. You can define relations client-side using ADO.NET.
select customerid, customername from customer;
select orderid, orderdate, customerid, orderamount from orders
two tables are returned and you use DataAdapter.Fill() to populate the Dataset.
The DataTable approach could be "simpler" than the DataSet approach but it really depends on your application's requirements. Read up on the Command, DataAdapter, DataTable, and DataSet objects. With ADO.NET you can solve the problem in a variety of ways.
Since the question is also tagged TSQL: you could create a stored procedure and execute that via the ADO Command too:
create proc getCustomerOrders
@customerid int
as
begin
select
customer.customerid, customername, orderid, orderdate, orderamount
from customer inner join orders
on customer.customerid = orders.customerid and customer.customerid = @customerid
end
