Exception: No suitable driver found for jdbc:product:oracle://mysite:1521;SID=mysid;

hi 

I am getting the below error when I try to make a connection to Oracle DB

No suitable driver found for jdbc:product:oracle://mysite:1521;SID=mysid;

my code is something like this:

Connection conn = DriverManager.getConnection(url_, user_, password_);

ResultSet resultSet=null;
resultSet = conn.createStatement().executeQuery("select * from projects" );

Please let me know what could be the problem.I am able to successfully connect to mssql db with the same code.

Thanks in advance

Sam