Recent questions tagged aggregation

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aggregation framework - What's the $unwind operator in MongoDB?

This is my first day with MongoDB so please go easy with me :) I can't understand the $unwind operator, maybe ... a simple array of tag names. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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638 views

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aggregation framework - How to aggregate sum in MongoDB to get a total count?

For some collection with a field { wins: Number }, how could I use MongoDB Aggregation Framework to get the total number ... , i.e. total: 25. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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558 views

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aggregation framework - How to sum every fields in a sub document of MongoDB?

I got a problem when I use db.collection.aggregate in MongoDB. I have a data structure like: _id:... Segment:{ "S1 ... } ]) but it doesn't work. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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606 views

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aggregation framework - Mongodb sort inner array

I've been looking for a while now and can't seem to sort an inner array and keep that in the doc that I'm ... ':1}}); Anyone think they can help on this? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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389 views

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aggregation framework - mongodb group values by multiple fields

For example, I have these documents: { "addr": "address1", "book": "book1" }, { "addr": "address2", "book": "book1 ... : 20 |... | book_M: 20 | total: M*20 Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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820 views

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aggregation framework - Creating a view with non aggregate field in mongodb without putting it in _id field

I have a collection with data given below { "_id" : ObjectId("5fc8a58257f6526c6a520725"), "job_id" : ObjectId(" ... non-aggregate-field-in-mongodb-without-putting-it-in-id-fi...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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513 views

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aggregation framework - Group by an optional field in mongodb

I would like to independently group the results of an or clause, including overlap. The data set is rather large ... .com/questions/65908030/group-by-an-optional-field-in-mongodb...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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570 views

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aggregation framework - how to use lookup along with $push in mongodb

I was playing with Mongodb and wanted a query that use lookup and $push or $addToSet See this https://mongoplayground ... /65915319/how-to-use-lookup-along-with-push-in-mongodb...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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736 views

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aggregation framework - Copy first array value to another field in MongoDB

I have an old list of products that store the descriptions in an array at index [0]. The model is set ... com/questions/65947153/copy-first-array-value-to-another-field-in-mongodb...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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600 views

1 answer

aggregation framework - How to flatten a subdocument into root level in MongoDB?

For example, if I have a document like this { a: 1, subdoc: { b: 2, c: 3 } } How can I ... .com/questions/22903849/how-to-flatten-a-subdocument-into-root-level-in-mongodb...

asked Oct 6, 2021 in Technique[技术] by 深蓝 (71.8m points)

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628 views

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aggregation framework - How to flatten a subdocument into root level in MongoDB?

For example, if I have a document like this { a: 1, subdoc: { b: 2, c: 3 } } How can I ... .com/questions/22903849/how-to-flatten-a-subdocument-into-root-level-in-mongodb...

asked Oct 6, 2021 in Technique[技术] by 深蓝 (71.8m points)

0 votes

601 views

1 answer

aggregation framework - MongoDB aggregate: count of elements in an object key

I have a MongoDB document like this: [ { "_id": { "$oid": "5ff09030cd55d6d9f378d460" }, "username": "a ... /questions/66062748/mongodb-aggregate-count-of-elements-in-an-object-key...

asked Oct 6, 2021 in Technique[技术] by 深蓝 (71.8m points)

0 votes

638 views

1 answer

aggregation framework - how to use lookup along with $push in mongodb

I was playing with Mongodb and wanted a query that use lookup and $push or $addToSet See this https://mongoplayground ... /65915319/how-to-use-lookup-along-with-push-in-mongodb...

asked Mar 6, 2021 in Technique[技术] by 深蓝 (71.8m points)

0 votes

579 views

1 answer

aggregation framework - how to use lookup along with $push in mongodb

I was playing with Mongodb and wanted a query that use lookup and $push or $addToSet See this https://mongoplayground ... /65915319/how-to-use-lookup-along-with-push-in-mongodb...

asked Mar 6, 2021 in Technique[技术] by 深蓝 (71.8m points)

0 votes

510 views

1 answer

aggregation - SQL Overwrite value in column in group by

lets say i have following sql-table fruit | amount | date ------------------------- apple | 2 | 2019 apple | 3 | ... | 2 | 2017 peach | 3 | 2017 Any ideas how to do this in sql?...

asked Feb 19, 2021 in Technique[技术] by 深蓝 (71.8m points)

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