Difference between Optimistic and Pessimistic locking

In Pessimistic locking when user wants to update data it locks the record and till then no one can update data. Other user’s can only view the data when there is pessimistic locking
In Optimistic locking multiple users can open the same record for updating, thus increase maximum concurrency. Record is only locked when updating the record

Difference between IN and BETWEEN, that are used inside a WHERE clause

   The BETWEEN clause is used to fetch a range of values, whereas the IN clause fetches data from a list of specified values.

Define Data Provider

A set of libraries  that is used to communicate with data source.
Eg: SQL data provider for SQL,  Oracle data provider for Oracle, OLE DB data provider for access, excel or   mysql.

New Features in ADO.NET Entity Framework 4.0

Today , we see the "New Features and Enhancements in ADO.NET Entity Framework 4.0"            ADO.NET Entity Framework 4.0 ships with Visual Studio 2010 and includes the following new features and enhancements:

1. persistence ignorance
2. lazy loading
3. self-tracking entities
4. POCO change tracking
5. model-first development
6. built-in functions and model-defined functions