it looks like you are trying to store it looks like your select list is a multiple select list which would mean that projects are stored as a comma separated list to the database.
this is a bad practice. this is not the correct way to create a many to many relationship
Nope, that's not how it is at all.
The projects records each include a project category field as an enum field. I have a recordset on that page that does a SELECT DISTINCT on that field - thus, the recordset ($row_WADAProject) thus contains a single instance of each project category. This recordset is used only to populate that select tag. As I'm stepping through that recordset I want to compare each project category to the category in the record specified by the passed ID, and when they match, add the "selected" attribute to the associated <option> tag.
Each project in the projects table will belong only to a single project category.
Does that help you understand what I am doing? I want a list of categories with the category applicable to the given record already selected.