I\'ve looked for an answer to this, but all I can find is people asking how to search all columns of ALL tables in a database for a value. I just want to search all columns
This sounds like you just want to know which table and column some data is stored, not that you want to know that during the execution of your code, or change it. I also had this problem and this solved it:
Download your database in SQL format (using phpmyadmin, for example), open it with a text editor and search for the occurrences you want.