Database Articles

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Find result within array of objects and match email address field in MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 316 Views

Let us first create a collection with documents −>db.demo144.insertOne({"EmployeeDetails":[{"EmployeeName":"Chris", "EmployeeEmail":"Chris12@gmail.com"}, {"EmployeeName":"Bob", "EmployeeEmail":"bo22@gmail.com"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32f1d8fdf09dd6d08539b9") } >db.demo144.insertOne({"EmployeeDetails":[{"EmployeeName":"David", "EmployeeEmail":"david@gmail.com"}, {"EmployeeName":"Carol", "EmployeeEmail":"Carol@gmail.com"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32f1f5fdf09dd6d08539ba") }Display all documents from a collection with the help of find() method −> db.demo144.find();This will produce the following output −{    "_id" : ObjectId("5e32f1d8fdf09dd6d08539b9"), "EmployeeDetails" : [       { "EmployeeName" : "Chris", "EmployeeEmail" : "Chris12@gmail.com" },       { "EmployeeName" : "Bob", "EmployeeEmail" : "bo22@gmail.com" }    ] } {    "_id" : ObjectId("5e32f1f5fdf09dd6d08539ba"), "EmployeeDetails" : [       { "EmployeeName" ...

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How do I $set and $push in single update with MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 911 Views

For this, simply use update() to update. Let us create a collection with documents −> db.dem0143.insertOne({"StudentId":1, "Details":{"Name":"Chris"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32eb9efdf09dd6d08539b7") } > db.dem0143.insertOne({"StudentId":2, "Details":{"Name":"David"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32eba5fdf09dd6d08539b8") }Display all documents from a collection with the help of find() method −> db.dem0143.find();This will produce the following output −{ "_id" : ObjectId("5e32eb9efdf09dd6d08539b7"), "StudentId" : 1, "Details" : { "Name" : "Chris" } } { "_id" : ObjectId("5e32eba5fdf09dd6d08539b8"), "StudentId" : 2, "Details" : { "Name" : "David" } }Following is the query to implement $set and $push in a single update ...

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Push query results into variable with MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 956 Views

For this, you can use aggregate(). Let us create a collection with documents −> db.demo142.insertOne({"Value":50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32e9c6fdf09dd6d08539b2") } > db.demo142.insertOne({"Value":45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32e9cafdf09dd6d08539b3") } > db.demo142.insertOne({"Value":60}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32e9cdfdf09dd6d08539b4") } > db.demo142.insertOne({"Value":55}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32e9d0fdf09dd6d08539b5") } > db.demo142.insertOne({"Value":50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e32e9d9fdf09dd6d08539b6") }Display all documents from a collection with the help of find() method −> db.demo142.find();This will produce the following output −{ "_id" : ObjectId("5e32e9c6fdf09dd6d08539b2"), "Value" : 50 } { ...

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MongoDB query to find last object in collection?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 6K+ Views

To find last object in collection, at first sort() to sort the values. Use limit() to get number of values i.e. if you want only the last object, then use limit(1).Let us first create a collection with documents −> db.demo141.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c347fdf09dd6d08539ae") } > db.demo141.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c34bfdf09dd6d08539af") } > db.demo141.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c34ffdf09dd6d08539b0") } > db.demo141.insertOne({"Name":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c352fdf09dd6d08539b1") }Display all documents from a collection with the help of find() method −> db.demo141.find();This will ...

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MongoDB: $nin and $in not working together in $elemMatch to fetch documents having subjects “MongoDB”, but not “Java”

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 337 Views

For such kind of fetching, use only $nin and $in. Let us create a collection with documents −> db.demo140.insertOne({"Id":101, "Subjects":["MongoDB", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c149fdf09dd6d08539a9") } > db.demo140.insertOne({"Id":102, "Subjects":["MongoDB", "Java"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c14cfdf09dd6d08539aa") } > db.demo140.insertOne({"Id":103, "Subjects":["MongoDB", "PL/SQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c157fdf09dd6d08539ab") } > db.demo140.insertOne({"Id":104, "Subjects":["MongoDB", "SQL Server"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c163fdf09dd6d08539ac") } > db.demo140.insertOne({"Id":105, "Subjects":["C", "C++"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31c16ffdf09dd6d08539ad") }Display all documents from a collection with the help of find() method −> ...

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How to retrieve all nested fields from MongoDB collection?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 1K+ Views

For this, use aggregate(). Let us create a collection with documents −>db.demo138.insertOne({"Id":101, "PlayerDetails":[{"PlayerName":"Chris", "PlayerScore":400}, {"PlayerName":"David", "PlayerScore":1000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31bb9ffdf09dd6d08539a1") } >db.demo138.insertOne({"Id":102, "PlayerDetails":[{"PlayerName":"Bob", "PlayerScore":500}, {"PlayerName":"Carol", "PlayerScore":600}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31bbcefdf09dd6d08539a2") }Display all documents from a collection with the help of find() method −> db.demo138.find();This will produce the following output −{    "_id" : ObjectId("5e31bb9ffdf09dd6d08539a1"), "Id" : 101, "PlayerDetails" : [       { "PlayerName" : "Chris", "PlayerScore" : 400 },       { "PlayerName" : "David", "PlayerScore" : 1000 }    ] } {    "_id" : ObjectId("5e31bbcefdf09dd6d08539a2"), ...

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How to compare two fields in aggregation filter with MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 2K+ Views

For this, use aggregate() along with $filter. Let us create a collection with documents −> db.demo137.insertOne( ...    { ...       Name1:"Chris", ...       Name2:"David", ...       Detail1:[ ...          {_id:"John", Name3:"Chris"}, ...          {_id:"Chris", Name3:"Chris"}, ...       ], ...       Detail2:[{_id:"David", Name3:"Chris"}, ...       {_id:"Carol", Name3:"Chris"}, ...       {_id:"John", Name3:"Chris"}] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31b4cefdf09dd6d08539a0") }Display all documents from a collection with the help of find() method −> db.demo137.find();This will ...

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How to update array of subdocuments in MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 2K+ Views

To update, use update() along with $set. Let us create a collection with documents −>db.demo134.insertOne({"EmployeeId":101, "EmployeeDetails":[{"EmployeeName":"Chris", "EmployeeAge":27}, {"EmployeeName":"Bob", "EmployeeAge":28}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e319b2f68e7f832db1a7f7c") } >db.demo134.insertOne({"EmployeeId":102, "EmployeeDetails":[{"EmployeeName":"David", "EmployeeAge":24}, {"EmployeeName":"Carol", "EmployeeAge":29}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e319b4468e7f832db1a7f7d") }Display all documents from a collection with the help of find() method −> db.demo134.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e319b2f68e7f832db1a7f7c"),    "EmployeeId" : 101,    "EmployeeDetails" : [       {          "EmployeeName" : "Chris",          "EmployeeAge" : 27       },       ...

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Group by day/month/week based on the date range in MongoDB

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 2K+ Views

To group, use $week and $month in MongoDB. Let us create a collection with documents −> db.demo133.insertOne({"Rank":18, "DueDate":new ISODate("2020-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31980968e7f832db1a7f78") } > db.demo133.insertOne({"Rank":12, "DueDate":new ISODate("2020-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31982568e7f832db1a7f79") } > db.demo133.insertOne({"Rank":12, "DueDate":new ISODate("2020-02-01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31986568e7f832db1a7f7a") } > db.demo133.insertOne({"Rank":20, "DueDate":new ISODate("2020-02-01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31986c68e7f832db1a7f7b") }Display all documents from a collection with the help of find() method −> db.demo133.find();This will produce the following output −{ "_id" : ObjectId("5e31980968e7f832db1a7f78"), "Rank" : 18, "DueDate" : ISODate("2020-01-10T00:00:00Z") } ...

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Group across two columns in MongoDB?

AmitDiwan
AmitDiwan
Updated on 31-Mar-2020 275 Views

To group across two columns, use $lookup. Let us create a collection with documents −> db.demo132.insertOne({"CountryName1":"US", "CountryName2":"UK", Value:50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31950468e7f832db1a7f75") } > db.demo132.insertOne({"CountryName1":"UK", "CountryName2":"AUS", Value:10}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31951d68e7f832db1a7f76") } > db.demo132.insertOne({"CountryName1":"AUS", "CountryName2":"US", Value:40}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31952c68e7f832db1a7f77") }Display all documents from a collection with the help of find() method −> db.demo132.find();This will produce the following output −{ "_id" : ObjectId("5e31950468e7f832db1a7f75"), "CountryName1" : "US", "CountryName2" : "UK", "Value" : 50 } { "_id" : ObjectId("5e31951d68e7f832db1a7f76"), "CountryName1" : "UK", "CountryName2" : "AUS", "Value" : ...

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