As you know that SQL is a Programming lang. of Database (Structured Query Language) without SQL, we can't login to any website and access our files. SQL is the most useable Pogramming lang. SQL is only use for Database Structuring storing info data. Now PHP (Hypertext Pre-processor or Personal Home Page) PHP is widely used in web applications to connect with Server, Web Applications and SQL DB. PHP is really very useful in Web Programming world, without PHP there could be nothing. Every Hackers need to learn PHP,SQL and SQLI (SQL Injection).