如何在MongoDB中选择字段总和大于某个值的位置 [英] How to select where sum of fields is greater than a value in MongoDB

问题描述

使用MongoDB，我将如何编写此常规SQL语句?

Using MongoDB, How would I write this regular SQL statement?

SELECT * FROM table WHERE (field1+field2+field3) > 1

我一直在弄乱$ group，$ project，$ add等.我觉得我在解决方案中四处跳舞，但无法弄清楚.

I've been messing with $group, $project, $add, etc. I feel like I'm dancing all around the solution but can't figure it out.

推荐答案

最简单的方法是使用

The easiest way to do this is by using $where (I am not telling that it is not possible to do this with aggregation)

db.table.find({$where: function() {
   return this.field1 + this.field2 + this.field3 > 1
   // most probably you have to handle additional cases if some of the fields do not exist.
}}

它的优点是简单直观，而缺点:

The pros of it is that it is easy and intuitive, whereas cons:

要求数据库处理JavaScript表达式或 集合中每个文档的功能.

requires that the database processes the JavaScript expression or function for each document in the collection.

如果您需要经常执行这种搜索，我将继续创建一个新字段，该字段中将存储3个字段的总和，并为其添加索引.缺点是您必须增加应用逻辑.

If you need to perform this kind of searches often, I would go ahead and create a new field which will have a sum of 3 fields stored in it and put an index on it. The downside is that you have to increase your app logic.

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