mongodb distinct match
Harder - Count with $project and $cond. Use project to create a 'hasCat' field. You will need to use $cond to do this: http://docs.mongodb. ,field, string, The field for which to return distinct values. query, document, A query that specifies the documents from which to retrieve the distinct values. options ... ,The name of the collection to query for distinct values. key, string, The field for which to return distinct values. query, document, Optional ... ,2015年12月15日 — Of course you can shorcut the selection in modern MongoDB releases after MongoDB 2.6 with the $$ROOT variable: Order.aggregate( [ "$match ... ,2013年10月29日 — Just a reminder, the result from MongoDB is sequence/array of documents. While a BSON array is internally extremely similar to a ... ,2017年10月11日 — You can use $group by arr with $sum in aggregation pipeline. db.mycoll.aggregate($group:_id:"$arr", count:$sum:1}}}). ,Since you are willing to group also by DOB , you shuld include it in the _id of your group , like this: db.ped.aggregate([ $match:"DOB-Year":2014} }, $group: ... ,2016年8月11日 — I understand the problem now, inorder to match/filter subdocuments we need to use $elemMatch operator, like this db.Article.distinct("Comment ... ,2019年8月28日 — ... the find and distinct operations in MongoDB with simple code examples. ... according to which the find operation will match the documents.
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 mongodb distinct match 相關參考資料
Counting distinct fields with $project and $match
Harder - Count with $project and $cond. Use project to create a 'hasCat' field. You will need to use $cond to do this: http://docs.mongodb. https://www.forwardadvance.com db.collection.distinct() - MongoDB Documentation
field, string, The field for which to return distinct values. query, document, A query that specifies the documents from which to retrieve the distinct values. options ... https://docs.mongodb.com distinct — MongoDB Manual
The name of the collection to query for distinct values. key, string, The field for which to return distinct values. query, document, Optional ... https://docs.mongodb.com Get distinct records with specified fields that match a value ...
2015年12月15日 — Of course you can shorcut the selection in modern MongoDB releases after MongoDB 2.6 with the $$ROOT variable: Order.aggregate( [ "$match ... https://stackoverflow.com match and distinct in single query mongodb - Stack Overflow
2013年10月29日 — Just a reminder, the result from MongoDB is sequence/array of documents. While a BSON array is internally extremely similar to a ... https://stackoverflow.com Mongo - Distinct match entire array - Stack Overflow
2017年10月11日 — You can use $group by arr with $sum in aggregation pipeline. db.mycoll.aggregate($group:_id:"$arr", count:$sum:1}}}). https://stackoverflow.com Mongodb aggregate with distinct - Stack Overflow
Since you are willing to group also by DOB , you shuld include it in the _id of your group , like this: db.ped.aggregate([ $match:"DOB-Year":2014} }, $group: ... https://stackoverflow.com mongoDB distinct & where in same query? - Stack Overflow
2016年8月11日 — I understand the problem now, inorder to match/filter subdocuments we need to use $elemMatch operator, like this db.Article.distinct("Comment ... https://stackoverflow.com MongoDB Find and Distinct | ObjectRocket
2019年8月28日 — ... the find and distinct operations in MongoDB with simple code examples. ... according to which the find operation will match the documents. https://kb.objectrocket.com |