Question

I have a products table with a column for price and master category.

I’d like to query my DB to find the range of prices there are for a given category (or all categories). This range of prices would then be broken into an appropriate number of price-ranges ie £0-£5 £5-£10 etc…

I can’t get my head around how to do this; do I need to do this all with php?

EDIT: having had a wee think about it, to clarify, I would like to end up so that whatever category is being listed, I can show perhaps 4 price ranges with roughly equal numbers of products in each. I can’t get my feeble mind around it 🙁

Answer 1

For the min and max price per category:

SELECT category, min(price) as min_price, max(price) as max_price
from Products
Group BY category

For ranges directly in a query you could do something like this

SELECT
    category,
    SUM(CASE WHEN price BETWEEN 0 AND 5 THEN 1 ELSE 0 END) as zero-five,
    SUM(CASE WHEN price BETWEEN 5 AND 10 THEN 1 ELSE 0 END) as five-ten,
    ...
from Products
Group BY category

yields

Category  zero-five  five-ten
Cat1        2          4
Cat2        3          6

or

SELECT category, range, count(*)
FROM (
    SELECT 
        category,
        CASE WHEN price BETWEEN 0 to 5 THEN '0-5'
             WHEN price BETWEEN 5 to 10 THEN '5-10'
             ...
             ELSE '10+'
        END as range
    FROM products
)
group by category, range

yields

Category  range count
Cat1       0-5    2      
Cat1       5-10   4      
Cat1       10+    0
Cat2       0-5    3      
Cat2       5-10   6      
Cat2       10+    0