Can you let me know what's wrong with this code?

Question

I have to display user specific information from MySQL on php. Credit and Balance are the 2 data that I have to display according to the user.
https://code.sololearn.com/wuiNc3PcY52D/?ref=app

Answer 1

Add status check to mysql_fetch_array()

Also:

if (isset($arr['Credit']))
{
// $arr['Credit'] is ok to use
}
else
{
// There's a problem
}

Do that isset() test on all array accessors.

Make your code more robust like that.

Add unit tests too, that will mean adding a stub for the database code, so you can decouple it. That way you can test different routes through your code, to check it's stability for unexpected situations.