LINQ Stand for Language Integrated Queries which is introduced by Microsoft for better database programs. with this brilliant technology we don't need to worry about connection setups and query writing.
First we need to create the database and the tables. then we can add a "linq to sql class" from new items menu. just after drag and drop the tables on to that class we have a complete class which refer to the relevant database. Now no need to write any query, creating an object of that class will enable you to do any thing to the database without Queries on your hand.
For the deep undesirability refer following links
2.LINQ Query Expressions