How would I find duplicate fields in a mongo collection. I’d like to check if any of the “name” fields are duplicates. { “name” : “ksqn291”, “__v” : 0, “_id” : ObjectId(“540f346c3e7fc1054ffa7086”), “channel” : “Sales” } Many thanks! 9 Answers 9
I am playing around with MongoDB trying to figure out how to do a simple SELECT province, COUNT(*) FROM contest GROUP BY province But I can’t seem to figure it out using the aggregate function. I can do it using some really weird group syntax db.user.group({ “key”: { “province”: true }, “initial”: { “count”: 0 … Read more
How can I (in MongoDB) combine data from multiple collections into one collection? Can I use map-reduce and if so then how? I would greatly appreciate some example as I am a novice. 11 Answers 11
I’d like to get the names of all the keys in a MongoDB collection. For example, from this: db.things.insert( { type : [‘dog’, ‘cat’] } ); db.things.insert( { egg : [‘cat’] } ); db.things.insert( { type : [] } ); db.things.insert( { hello : [] } ); I’d like to get the unique keys: type, … Read more
Suppose you have the following documents in my collection: { “_id”:ObjectId(“562e7c594c12942f08fe4192”), “shapes”:[ { “shape”:”square”, “color”:”blue” }, { “shape”:”circle”, “color”:”red” } ] }, { “_id”:ObjectId(“562e7c594c12942f08fe4193”), “shapes”:[ { “shape”:”square”, “color”:”black” }, { “shape”:”circle”, “color”:”green” } ] } Do query: db.test.find({“shapes.color”: “red”}, {“shapes.color”: 1}) Or db.test.find({shapes: {“$elemMatch”: {color: “red”}}}, {“shapes.color”: 1}) Returns matched document (Document 1), but always … Read more
In MongoDB, is it possible to update the value of a field using the value from another field? The equivalent SQL would be something like: UPDATE Person SET Name = FirstName + ‘ ‘ + LastName And the MongoDB pseudo-code would be: db.person.update( {}, { $set : { name : firstName + ‘ ‘ + … Read more
