Mongo字段A大于字段B [英] Mongo field A greater than field B

问题描述

我正在Mongo中尝试一个简单的查询，在MySQL中看起来像这样.

i'm trying a simple query in Mongo which in MySQL would look like this.

select * from emails where bounceCount > sentCount;

到目前为止，我有.

db.email.find({ bounceCount : { $gt : sentCount } } );

但是我得到这个错误

JS Error: ReferenceError: sentCount is not defined (shell):0

如何在该shell中引用sendCount?

How do I reference the sentCount in that shell?

推荐答案

每个人似乎都在不真正知道$where的情况下提到了$where:

Everyone seems to mention $where without really knowing that it is:

• 慢
• 不安全(逃避)
• JavaScript，而不是MongoDB内部
• 并且，在2.4之前的版本中，单线程和全局锁定

另一种在大约99％的情况下会更好的方法是使用聚合框架:

Another method which would be a lot better for about 99% of cases is to use the aggregation framework:

db.col.aggregate([
    {$project: {ab: {$cmp: ['$bounceCount','$sentCount']}}},
    {$match: {ab:{$gt:0}}}
])

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