You can enter as many newlines as you want until you complete a statement, terminated with a semicolon; it's not an error, just a form of multi-line input which is common to command-line SQL interpreters. I'm not sure why entering a semicolon didn't work for you. Maybe you had an unterminated string literal or identifier? I'm not sure how to cancel a statement, though. Ctrl+D? Ctrl+C? Someone else surely knows.