How do I create a SQL query that groups in certain percent range

Question

I would like to create a SQL query that groups the increase price of items in certain percentage range. For example

2 items increased between 0 to 10 %

4 items i

Answer 1

SELECT SUM(CASE WHEN PercentChange >= 0 AND PercentChange <= 10 THEN 1 ELSE 0) END AS ZeroTen,
       SUM(CASE WHEN PercentChange > 10 AND PercentChange <= 20 THEN 1 ELSE 0) END AS TenTwenty,
       SUM(CASE WHEN PercentChange > 20 AND PercentChange <= 30 THEN 1 ELSE 0) END AS TwentyThirty
    FROM MagicChangeTable

Note: MagicChangeTable may in fact be a subquery to calculate the percent change.

Answer 2

If You want all ranges by 10: Use:

SELECT (d-10)*10 AS `from` , (d-9)*10 AS `to` , c AS `count` FROM 
   (SELECT DISTINCT(FLOOR((`p`.`new`*10)/(`p`.`old`))) AS d,
      count(1) AS c FROM prices as p GROUP BY 1) AS stats

for such structure:

CREATE TABLE `prices` (
  `old` int(11) NOT NULL,
  `new` int(11) NOT NULL
);

edit: >=from and < to