Added more rows to results output, fixed validation to use strlen > 0 rather than isset as even if no input the variable through  is still set
Added stock and revenue rows, coded added to calculate total sales of a wine_id to get revenue, grouped by wine_id ordered by cost ASC;
Added code to allow user to restrict range of results by stock levels
 Removed max values for stock form, added minumum stock ordered
Added functionality to sort by minimum total stock sold
Removed Javascript validation, as PHP handles it now
Results ordered by wine_name now