几行之间的SQLite SUM（） [英] SQLite SUM() between several rows

问题描述

我需要一些帮助，在Android应用程序的SUM功能。我有一个表，看起来像下面这样：

I need some help with the SUM feature in android app. I have a table that looks something like the following :

我需要 SUM 最后两个记录笔记和与注意最后一条记录的数量。我需要总结的行数量31,32和33这将返回90.我试过

I have need to SUM Quantities between last two records Notes and last one record with Note. I need to sum Quantity of rows 31,32 and 33. It would return 90. I've tried

SELECT Sum(QUANTITY) FROM fuel_table WHERE NOTE!='' ORDER BY ID DESC

但它返回的所有量总和与注意事项。

but it returns SUM of all quantities with note.

推荐答案

我倾向于短语的问题是：从金额有一个音符超前他们中的所有行的数量。这表明：

I am inclined to phrase the question as: sum the quantity from all rows that have one note "ahead" of them. This suggests:

select sum(quantity)
from (select ft.*,
             (select count(*)
              from fuel_table ft2
              where ft2.note = 'Yes' and ft2.id >= ft.id
             ) as numNotesAhead
      from fuel_table ft
     ) ft
where numNotesAhead = 1;

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