mongodb subquery
Mongodb does not allow for sub queries or joins. You will have to break things up into two queries from your application code. If you want to find all the books that a given userid has liked, you could do that with a single sub select query in SQL like: S, If I understand correctly you have two collections like this. collection1 [ "c" : 3, "field" : 3 }, "b" : 2, "field" : 2 }, "a" : 1, "field" : 1 } ]. collection2
| 相關軟體 MongoDB 資訊 | |
|---|---|
 mongodb subquery 相關參考資料
How to implement sql subquery in mongo aggregation pipeline ...
Given the following sample data: db.collection.insert([ "name": "Peter", "age": 1 }, "name": "Peter", "age": 10 }, "name": &qu... https://stackoverflow.com How to perform subqueries in MongoDB - Quora
Mongodb does not allow for sub queries or joins. You will have to break things up into two queries from your application code. If you want to find all the books that a given userid has liked, you coul... https://www.quora.com Issue with subquery in mongoDB - Stack Overflow
If I understand correctly you have two collections like this. collection1 [ "c" : 3, "field" : 3 }, "b" : 2, "field" : 2 }, "a" : 1, "field&q... https://stackoverflow.com lookup - MongoDB Documentation
To perform uncorrelated subqueries between two collections as well as allow other join ... Specify Multiple Join Conditions with $lookup; Uncorrelated Subquery ... https://docs.mongodb.com Make a sub query MongoDB - jaffar cardoso - Medium
How to make a subquery using mongodb without any link, without any reference.. “Make a sub query MongoDB” is published by jaffar cardoso. https://medium.com MongoDB - simple sub query example - Stack Overflow
You can do this within a single query using the aggregation framework. In particular you'd need to run an aggregation pipeline that uses the ... https://stackoverflow.com Query on EmbeddedNested Documents — MongoDB Manual
This page provides examples in: Mongo Shell; Compass; Python; Java (Sync); Node.js; PHP; Motor; Java (Async); C#; Perl ... https://docs.mongodb.com Sub-query in MongoDB - Stack Overflow
No Joins in here, just us bears. So MongoDB "does not do joins". You might have tried something like this in the shell for example: https://stackoverflow.com Subquery in MongoDB - Stack Overflow
I guess you could do a 2 step aggregation, in the first step accumulate names and contests into sets, and in the first get the length https://stackoverflow.com |