30. The first database query Linq

 

Query the database using Linq to Entity

First, add the ADO.NET Entity Data Model in the project, as follows

 

New Connection

Check the resulting table

Click Finish to see the two entity data object model established

 

 

 After a good model generation can be used directly

            CustomerOrderEntities entity = new CustomerOrderEntities();
            var queryResult = from n in entity.tblCustomer where n.Region =="Asia" select new { n.CustomerName,Orders= n.btlOrder};

            foreach (var item in queryResult)
            {
                Console.WriteLine(item.CustomerName);
                foreach (btlOrder o in item.Orders)
                    Console.WriteLine("orderId:" + o.OrderId + " Amount:" + o.Qty * o.Price);
            }