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Articles on Trending Technologies
Technical articles with clear explanations and examples
Fetch all the ids of MongoDB documents?
To fetch all the ids, simply use find() in MongoDB. Let us create a collection with documents −> db.demo169.insertOne({"StudentName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e36975e9e4f06af551997d7") } > db.demo169.insertOne({"StudentName":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3697629e4f06af551997d8") } > db.demo169.insertOne({"StudentName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3697679e4f06af551997d9") }Display all documents from a collection with the help of find() method −> db.demo169.find();This will produce the following output −{ "_id" : ObjectId("5e36975e9e4f06af551997d7"), "StudentName" : "Chris" } { "_id" : ObjectId("5e3697629e4f06af551997d8"), "StudentName" : "Bob" } { "_id" : ObjectId("5e3697679e4f06af551997d9"), "StudentName" : "David" }Following is the query to get ...
Read MoreMongoDB query to return only specific fields (phone numbers) in the form of an array?
Let us create a collection with documents −> db.demo166.insertOne({"details" : { "UserName" : "Chris", "UserAge":29, "PhoneDetails" : { "PhoneNumber" : "98646463533" } } }); { "acknowledged" : true, "insertedId" : ObjectId("5e368b159e4f06af551997cf") } > db.demo166.insertOne({"details" : { "UserName" : "David", "UserAge":21, "PhoneDetails" : { "PhoneNumber" : "87664534654" } } }); { "acknowledged" : true, "insertedId" : ObjectId("5e368b159e4f06af551997d0") }Display all documents from a collection with the help of find() method −> db.demo166.find();This will produce the following output −{ "_id" : ObjectId("5e368b159e4f06af551997cf"), "details" : { "UserName" : "Chris", "UserAge" : 29, "PhoneDetails" : { "PhoneNumber" : "98646463533" } } ...
Read MoreMongoDB query with $all in array
In MongoDB, $all is used to select the documents where the value of a field is an array that contains all the specified elementsLet us create a collection with documents −> db.demo163.insertOne( ... { ... "ClientDetails": [{ ... "ClientName": "Chris" ... ... }, { ... "ClientName": "David" ... ... } ... ] ... ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e3686d49e4f06af551997c5") } > db.demo163.insertOne( ... { ... "ClientDetails": [{ ... ...
Read MoreUpdating a MongoDB document and adding new keys only in the first document?
This can be easily achieved using MongoDB update(). Let us create a collection with documents −> db.demo162.insertOne({"StudentName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3684359e4f06af551997c2") } > db.demo162.insertOne({"StudentName":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3684389e4f06af551997c3") } > db.demo162.insertOne({"StudentName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e36843c9e4f06af551997c4") }Display all documents from a collection with the help of find() method −> db.demo162.find();This will produce the following output −{ "_id" : ObjectId("5e3684359e4f06af551997c2"), "StudentName" : "Chris", "StudentAge" : 23 } { "_id" : ObjectId("5e3684389e4f06af551997c3"), "StudentName" : "Bob" } { "_id" : ObjectId("5e36843c9e4f06af551997c4"), "StudentName" : "David" }Here is the query to ...
Read MoreSearch for multiple documents in MongoDB?
To search for multiple documents in MongoDB, use $in. Let us create a collection with documents −> db.demo161.insertOne({"ClientId":101, "ClientName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577cafdf09dd6d0853a09") } > db.demo161.insertOne({"ClientId":102, "ClientName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577d0fdf09dd6d0853a0a") } > db.demo161.insertOne({"ClientId":103, "ClientName":"David", "ClientAge":35}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577dffdf09dd6d0853a0b") } > db.demo161.insertOne({"ClientId":104, "ClientName":"Carol", "ClientAge":31}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577eefdf09dd6d0853a0c") }Display all documents from a collection with the help of find() method −> db.demo161.find();This will produce the following output −{ "_id" : ObjectId("5e3577cafdf09dd6d0853a09"), "ClientId" : 101, "ClientName" : "Chris" } { ...
Read MoreGroupBy Date in MongoDB to count duplicate date records
To count duplicate date records in MongoDB, use aggregate() and $group. Let us create a collection with documents −> db.demo160.insertOne({"DueDate":new ISODate()}); { "acknowledged" : true, "insertedId" : ObjectId("5e357525fdf09dd6d0853a04") } > db.demo160.insertOne({"DueDate":new ISODate("2019-01-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357532fdf09dd6d0853a05") } > db.demo160.insertOne({"DueDate":new ISODate()}); { "acknowledged" : true, "insertedId" : ObjectId("5e357534fdf09dd6d0853a06") } > db.demo160.insertOne({"DueDate":new ISODate("2019-01-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357538fdf09dd6d0853a07") } > db.demo160.insertOne({"DueDate":new ISODate("2020-04-10")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357542fdf09dd6d0853a08") }Display all documents from a collection with the help of find() method −> db.demo160.find();This will produce the following ...
Read MoreGet execution stats in MongoDB for a collection
To get stats, use explain() in MongoDB. Let us create a collection with documents −> db.demo157.insertOne({"Status":"Active"}); { "acknowledged" : true, "insertedId" : ObjectId("5e354fdffdf09dd6d08539fc") } > db.demo157.insertOne({"Status":"InActive"}); { "acknowledged" : true, "insertedId" : ObjectId("5e354fe3fdf09dd6d08539fd") }Display all documents from a collection with the help of find() method −> db.demo157.find();This will produce the following output −{ "_id" : ObjectId("5e354fdffdf09dd6d08539fc"), "Status" : "Active" } { "_id" : ObjectId("5e354fe3fdf09dd6d08539fd"), "Status" : "InActive" }Following is how to implement explain() in MongoDB −> db.demo157.find({Status: { $in: ['Active', 'InActive'] }}).explain("executionStats");This will produce the following output −{ "queryPlanner" : { "plannerVersion" ...
Read MoreHow to sort by the difference in array contents in MongoDB?
To sort by difference, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo155.insertOne({"Scores":[{"Value":45}, {"Value":50}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e354584fdf09dd6d08539e3") } > db.demo155.insertOne({"Scores":[{"Value":60}, {"Value":10}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e35458efdf09dd6d08539e4") } > db.demo155.insertOne({"Scores":[{"Value":100}, {"Value":95}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e354599fdf09dd6d08539e5") }Display all documents from a collection with the help of find() method −> db.demo155.find();This will produce the following output −{ "_id" : ObjectId("5e354584fdf09dd6d08539e3"), "Scores" : [ { "Value" : 45 }, { "Value" : 50 } ] } { "_id" : ObjectId("5e35458efdf09dd6d08539e4"), "Scores" : [ { "Value" ...
Read MoreQuery a nested field within an array with MongoDB
To query a nested field within an array, use $elemMatch in MongoDB. Let us create a collection with documents −> db.demo153.insertOne({"ClientDetails":[{"ClientName":"Chris", "ClientProject":"Online Banking System"}, {"ClientName":"David", "ClientProject":"Online School Management"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e351957fdf09dd6d08539df") } > db.demo153.insertOne({"ClientDetails":[{"ClientName":"Carol", "ClientProject":"Online Book System"}, {"ClientName":"Mike", "ClientProject":"Game Development"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3519c9fdf09dd6d08539e0") }Display all documents from a collection with the help of find() method −> db.demo153.find();This will produce the following output −{ "_id" : ObjectId("5e351957fdf09dd6d08539df"), "ClientDetails" : [ { "ClientName" : "Chris", "ClientProject" : "Online Banking System" }, { "ClientName" ...
Read MoreMongoDB query to update an array using FindAndUpdate()?
To update an array, instead use findAndModify() in MongoDB. Let us create a collection with documents −> db.demo152.insertOne({"id":102, "Name":["Chris", "David"], Score:45}); { "acknowledged" : true, "insertedId" : ObjectId("5e3515bcfdf09dd6d08539dd") } > db.demo152.insertOne({"id":103, "Name":["Mike", "Carol"], Score:65}); { "acknowledged" : true, "insertedId" : ObjectId("5e3515cafdf09dd6d08539de") }Display all documents from a collection with the help of find() method −> db.demo152.find();This will produce the following output −{ "_id" : ObjectId("5e3515bcfdf09dd6d08539dd"), "id" : 102, "Name" : [ "Chris", "David" ], "Score" : 45 } { "_id" : ObjectId("5e3515cafdf09dd6d08539de"), "id" : 103, "Name" : [ "Mike", "Carol" ], "Score" : 65 }Following is the ...
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