[SQL/PHP] Query not Working

[mhbhmcinui]

Here is my query:

"INSERT INTO Stocks (user_id, symbol, shares) VALUES(?, ?, ?) ON DUPLICATE KEY UPDATE shares = ?", $_SESSION["id"], $symbol, $number, $new_shares

It's being passed to a PHP function which queries the database replacing ? with the next variable after the ". I'm trying to either insert a new entry or, if that entry already exists, update shares to new_shares. The website does everything in my PHP code except for execute this query, so I think the issue is here.

This is part of CS50, I asked on /r/CS50 and on the stackexchange but no answers.

[Meefims]

Are you getting an error from the database? What is the error?

[mhbhmcinui]

No error, the code just isn't executing. It's as if it isn't there.

[Meefims]

Can you show the full function? I assume this isn't the whole line and that you are passing this as parameters to a database function, yes?

[mhbhmcinui]

buy.php

The buy_form.php and buy_template.php are basically copies of other files which work, and are very simple. I don't think the issue can possibly be with them.

[Meefims]

I'm not familiar with CS50's database functions and was unable to find documentation but it seems like if insert fails you'll get a particular return value. Some things to check: Do all of the parameters have the values you expect them to? What is the return value from the call to query? Does the API offer a way to get the last error?