在某些结果后如何添加总行数？

Question

我需要在每个月的搜索结果后添加总计行，例如：

Month   ID  Mod1    Mod2    Mod3
2014/1  1   5       4       2
2014/1  2   1       5       3
Total       6       9       5
2014/2  3   6       3       2
2014/2  4   2       1       4
Total       8       4       6

这是我的查询，没有总计行：

SELECT
  id_user,
  month,
  year,
  SUM(IF(mod = 1, 1, 0)) AS mod_1,
  SUM(IF(mod = 2, 1, 0)) AS mod_2,
  SUM(IF(mod = 3, 1, 0)) AS mod_3
FROM
  DW_RM_Log
WHERE
  year = 2014
GROUP BY
  year, month, id_user
ORDER BY
  year, month

如何在MySQL中执行此操作？

Answer 1

您可以将GROUP BY查询与ROLLUPS结合使用：

SELECT
  CASE WHEN id_user IS NOT NULL THEN CONCAT(`year`, '/', `Month`)
                                ELSE 'Total' END AS `Year_Month`,
  id_user,
  SUM(IF(`mod` = 1, 1, 0)) AS mod_1,
  SUM(IF(`mod` = 2, 1, 0)) AS mod_2,
  SUM(IF(`mod` = 3, 1, 0)) AS mod_3
FROM
  DW_RM_Log
WHERE
  `year` = 2014
GROUP BY
  `year`, `month`, id_user
WITH ROLLUP
HAVING `year` IS NOT NULL AND `month` IS NOT NULL

请看这里的小提琴。