Du får väl hitta på lite konventioner
if @ggr = '#' -- bara numeriska
SELECT prod_id, prod_title
FROM products
WHERE prod_cate_id = 2
AND left(prod_title, 1) between '0' and '9'
ORDER BY prod_title
else if @ggr = '%' -- vad som helst
SELECT prod_id, prod_title
FROM products
WHERE prod_cate_id = 2
ORDER BY prod_title
else if @ggr = '&' -- ej bokstav
SELECT prod_id, prod_title
FROM products
WHERE prod_cate_id = 2
AND left(prod_title, 1) not between 'A' and 'Z'
AND left(prod_title, 1) not in ('Å','Ä','Ö')
ORDER BY prod_title
else
SELECT prod_id, prod_title
FROM products
WHERE prod_cate_id = 2
AND left(prod_title, 1) = @grr
ORDER BY prod_title