LINQ TO SQL

ENTITY FRAMEWORK

-     Works only with SQL SERVER

-  Database agnostic (3rd party providers already available)

-     Limited Mapping Capabilities (mainly 1:1 mapping with database schema with the exception of one kind of inheritance ( Table per Hierarchy) where you have a single table used to represent the parent type and all child types and types are differentiated using a discriminator column in the database

-  More mapping scenarios supported:

- Table per Hierarchy (as LINQ To SQL)

- Table per Concrete Type: a separate table for each class or type in the hierarchy

- Table per SubClass: a hybrid approach using a shared table for information about the base type and separate tables for information about the derived types (entity splitting)

-    Support complex types: a type nested within a larger Entity and doesn’t have its own separate entity (for example type Address with street, city, state, country, …)I

LINQ TO SQL

ENTITY FRAMEWORK

Support at context level

DataLoadOptions dataLoadOptions = new DataLoadOptions();

dataLoadOptions.LoadWith<Customer>(c => c.Order);

dataLoadOptions.LoadWith<Order>(c => c.OrderDetail);

db.LoadOptions = dataLoadOptions;

List<Customer> customers = db.Customer.ToList();

Support at query level

Customer firstCustomer = db.Customer.Include("Order").Include("OrderDetails").First();

LINQ TO SQL

ENTITY FRAMEWORK

Automatic Deferred Loading enabled per default

In the example below, you are really only querying for  objects from the Products table – however, because Deferred Loading is enabled, you can access prod.SalesOrderDetail

var products = 

  from prod in db.Products
  where prod.Color == "Blue" 
  select prod;

foreach (Product prod in products)
{
 foreach (SalesOrderDetail detail 
            in prod.SalesOrderDetail)
 {
    // do something with detail
 }
}

Is it possible to disable deferred loading… 
db.DeferredLoadingEnabled = false;

Does not provide an automatic deferred loading mechanism

var products = 

   from prod in db.Product
   where prod.Color == "Blue"
   select prod;

foreach (Product prod in products)
{
  // avoids unnecessary queries
  if (!prod.SalesOrderDetail.IsLoaded)
  {
    prod.SalesOrderDetail.Load();
  } 

  foreach (SalesOrderDetail detail in 
        prod.SalesOrderDetail)
  {
     // do something with detail
  }
}