I am enthusiastic to enter the world of Databases through SQL, but I don’t know if there’s prerequisites of any significance and I only know C# and Java.
Besides these, what tools do I need? I have Visual Studio 2008 and SQL Server Management Studio. What else do I need? Is it necessary to download a server OS?
Visual Studio 2008 and SQL Server Express are sufficient to learn the basics of a Relational Database Management System (RDBMS.) You can learn T-SQL (SQL Server’s ANSI-SQL dialect,) schema design, Object-Relational Mapping, and more. SQL Express runs on Windows XP, Vista and Windows 7.
Oracle also provides an Express version, and there are other free options such as MySQL and SQLite.