如何在SQLite查询中计算正在运行的SUM？ [英] How do I calculate a running SUM on a SQLite query?

问题描述

如何获取一列，该列是另一列之前的所有值的总和？

How do I get a column that is the sum of all the values before of another column?

推荐答案

通过将表本身与表连接起来（执行所谓的笛卡尔或交叉联接）。参见下面的示例。

You can do it by joining the table with itself (performing a so-called Cartesian or cross join). See the following example.

SELECT a.name, a.gdppc, SUM(b.gdppc)
FROM gdppc AS a, gdppc AS b WHERE b.gdppc <= a.gdppc 
GROUP BY b.id ORDER BY a.gdppc;

给出一个包含国家及其人均GDP的表格，它将为您提供GDP总量的总和

Given a table containing countries and their per capita GDP it will give you a running total of the GDP figure.

Democratic Republic of Congo|329.645|329.645
Zimbabwe|370.465|700.11
Liberia|385.417|1085.527
Burundi|399.657|1485.184
Eritrea|678.954|2164.138
Niger|711.877|2876.015
Central African Republic|743.945|3619.96
Sierra Leone|781.594|4401.554
Togo|833.803|5235.357
Malawi|867.063|6102.42
Mozambique|932.511|7034.931
...

请注意，这可能会占用大量资源，因为如果表中包含N个元素，它将创建一个包含N * N个元素的临时表。我不会在大桌子上执行它。

Note that this can be a very resource-intensive operation, because if a table has N elements it will create a temporary table with N*N elements. I would not perform it on a large table.

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