Question

I’m trying to group results by a certain number in sql. i.e. if I have 60 lines and I want to group by groups of ten, I will have six groups of ten lines in them, reflecting the current order of the results in the table (in each group I will have the total or average of the lines in that group). Is there a way to do this?

Answer 1

MS SQL (sqlfiddle):

WITH cte(groupNumber, Id) AS
(
  SELECT
    (ROW_NUMBER( ) OVER ( ORDER BY Id )) / 10 AS groupNumber,
    Id
  FROM
    MyTable
)
SELECT
  MAX( Id ),
  groupNumber
FROM
  cte
GROUP BY
  groupNumber;

MySQL (sqlfiddle):

SELECT
  MAX( Id ),
  groupNumber
FROM
  (
    SELECT
      Id,
      CAST( FLOOR( (@a := @a + 1 ) / 10 ) AS UNSIGNED ) AS groupNumber
    FROM
      MyTable
    ORDER BY
      Id
  ) AS tmp,
  (SELECT @a := 0) r
GROUP BY
  groupNumber;