在 MySQL 中创建累积和列

2022-01-30 00:00:00 sql cumulative-sum mysql

我有一张如下所示的表格:

I have a table that looks like this:

id   count
1    100
2    50
3    10

我想添加一个名为cumulative_sum 的新列，因此表格如下所示:

I want to add a new column called cumulative_sum, so the table would look like this:

id   count  cumulative_sum
1    100    100
2    50     150
3    10     160

是否有一个 MySQL 更新语句可以轻松做到这一点?完成此任务的最佳方法是什么?

Is there a MySQL update statement that can do this easily? What's the best way to accomplish this?

推荐答案

如果性能是个问题，你可以使用 MySQL 变量:

If performance is an issue, you could use a MySQL variable:

set @csum := 0;
update YourTable
set cumulative_sum = (@csum := @csum + count)
order by id;

或者，您可以删除 cumulative_sum 列并在每个查询中计算它:

Alternatively, you could remove the cumulative_sum column and calculate it on each query:

set @csum := 0;
select id, count, (@csum := @csum + count) as cumulative_sum
from YourTable
order by id;

这以运行方式计算运行总和:)

This calculates the running sum in a running way :)

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