debug some PHP code on a single page

I have PHP page displaying data from MySQL. I have forms that allows folks to search the table by subject, levels, etc... as well as set the number of records to be displayed on one page. I have a problem with the latter 'number of records' filter with URL queries that use arrays. I've been plugging away for hours, but I imagine real programmer could fix it in minutes. Also... there are checkboxes in this form that I would like to remain checked when the query is run. Thanks for reading!