CHECKING if a value exists in a table SQL

I am making a bot where I need to store the commandname and commandreply in the database. I am using mySQL Workbench.

I want to check if the commandname that the user tries to make is already in the table, and if so display that. If not, then carry on (make the command).

connection.query("SELECT commandname FROM commands WHERE EXISTS (commandname = " + args[0] + ")" 

(Where args[0] is the command name). This is what I initially thought, although I don't have much experience in SQL. I'm not sure what this would display if it exists, or if it doesn't exist.

via Rusty