You may heard about Sql Injection or this is new word for you now.  In this post i am going to guide to Hack the website using the SQL Injection.

What is SQL?
  SQL is acronym of Structured Query Language.  SQL is common language for communicating with the Database.

What is SQL Injection?
A SQL injection attack consists of insertion or "injection" of a SQL query via the input data from the client to the application. A successful SQL injection exploit can read sensitive data from the database, modify database data (Insert/Update/Delete), execute administration operations on the database (such as shutdown the DBMS), recover the content of a given file present on the DBMS file system and in some cases issue commands to the operating system. SQL injection attacks are a type of injection attack, in which SQL
commands are injected into data-plane input in order to effect the execution of predefined SQL commands.

By doing this you can get the admin id and password.  after getting the Username and password you can access the control panel of admin and change the website details or whatever you like,you can do.