You're lacking a database connection in your function. Add the following to the very beginning of your function:
When you add
global $base to your function you'll be able to use it within your function without having to re-write the whole thing.
Unrelated note, but worth mentioning.
You are open to SQL injections and you're not using prepared statements as you should. You should be using placeholders and binding them later instead of passing they directly into your query.
And a tip for next time:
State in your question what isn't working. What your expectation is and what actually happens.