Dotaz MySQL pro seskupení dat do různých rozsahů

Musíte sestavit inline tabulku obsahující všechny cenové rozpětí. Poté proveďte LEFT JOIN s odvozenou tabulkou založenou na vašem dotazu, abyste získali očekávaný výsledek:

SELECT x.PriceRange, COALESCE(TotalWithinRange, 0) AS TotalWithinRange
FROM (
  SELECT "0 - 10" AS PriceRange 
  UNION SELECT "10 - 20"
  UNION SELECT "20 - 30"
  UNION SELECT "30 - 40"
  UNION SELECT "40 - 50"
  UNION SELECT "over 50" ) x
LEFT JOIN (  
   SELECT
      CASE when price >= 0 and price <= 10 then "0 - 10"
           when price > 10 and price <= 20 then "10 - 20"
           when price > 20 and price <= 30 then "20 - 30"
           when price > 30 and price <= 40 then "30 - 40"
           when price > 40 and price <= 50 then "40 - 50"
           else "over 50"
      END AS PriceRange,
      COUNT(*) as TotalWithinRange
   FROM YourTable
   GROUP BY 1 ) y ON x.PriceRange = y.PriceRange

Ukázka SQL Fiddle