AmitDiwan has Published 4112 Answers

MongoDB: combining AND and OR?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 14:04:26
Let us first create a collection with documents −> db.demo293.insertOne({FirstName:"Chris", LastName:"Brown", Age:24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4d45075d93261e4bc9ea32") } > db.demo293.insertOne({FirstName:"David", LastName:"Miller", Age:23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4d45265d93261e4bc9ea33") } > db.demo293.insertOne({FirstName:"John", LastName:"Smith", Age:24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4d45385d93261e4bc9ea34") } ... Read More

MongoDB - How to check for equality in collection and in embedded document?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:54:52
For this, check using $where in MongoDB. Let us create a collection with documents −> db.demo292.insertOne({FirstName:"Chris", LastName:"Brown", ...   "Friend":{FirstName:"David", "LastName":"Miller"} ...   } ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c10aa5d93261e4bc9ea30") } > db.demo292.insertOne({FirstName:"John", LastName:"Doe", ...   "Friend":{FirstName:"Mike", "LastName":"Doe"} ...} ...); {    "acknowledged" : true,   ... Read More

MongoDB - How to get the sum of two columns and save it to another column?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:51:43
To get the sum of two columns, use $add. Let us create a collection with documents −> db.demo291.insertOne({"Value1":10, "Value2":50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c0e1e5d93261e4bc9ea2f") }Display all documents from a collection with the help of find() method −> db.demo291.find();This will produce the following output −{ "_id" : ... Read More

MongoDB query for exact match

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:49:55
For exact match, you can use $exists that checks for a match. Let us create a collection with documents −> db.demo290.insertOne({"ListOfName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c0c9e5d93261e4bc9ea2d") } > db.demo290.insertOne({"ListOfName":["Chris", "David"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c0cb05d93261e4bc9ea2e") }Display all documents from a collection with ... Read More

Make an array of multiple arrays in MongoDB?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:48:24
To make an array of multiple arrays, use $unwind in MongoDB aggregate. Let us create a collection with documents −> db.demo289.insertOne({"Section":["A", "B", "E"], "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c06fcf49383b52759cbc3") } > db.demo289.insertOne({"Section":["C", "D", "B"], "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c070af49383b52759cbc4") }Display all ... Read More

Implement MongoDB $push in embedded document array?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:45:57
Let us create a collection with documents −>db.demo288.insertOne({"Name":"Chris", details:[{"CountryName":"US", Marks:78}, {"CountryName":"UK", Marks:68}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4c0393f49383b52759cbbe") }Display all documents from a collection with the help of find() method −> db.demo288.find();This will produce the following output −{ "_id" : ObjectId("5e4c0393f49383b52759cbbe"), "Name" : "Chris", "details" : [ ... Read More

MongoDB query to get only distinct values

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:44:46
To get distinct values, use distinct() in MongoDB. It finds the distinct values for a specified field across a single collection or view and returns the results in an array.Let us create a collection with documents −> db.demo287.insertOne({"details":{"AllVowels":["a", "u", "u", "o", "e", "a", "o", "i"]}}); {    "acknowledged" : true, ... Read More

Min and max values of an array in MongoDB?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:42:16
To get the min and max values, use $min and $max. Let us create a collection with documents −> db.demo286.insertOne({"details":[{Value1:70, Value2:50}, {Value1:30, Value2:36}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ac743f49383b52759cbbc") }Display all documents from a collection with the help of find() method −> db.demo286.find().pretty();This will produce the following ... Read More

What is the BSON query for the command 'show dbs' (list of databases) in MongoDB?

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:40:47
The command you can use is db.runCommand(). Let us first switch to admin −> use admin switched to db adminNow, run the command −> db.runCommand({listDatabases : 1})This will produce the following output −{    "databases" : [       {          "name" : "admin",     ... Read More

MongoDB query to limit subdocuments having the given fields of the 'projection'

AmitDiwan
AmitDiwan
Published on 31-Mar-2020 13:36:12
For this, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo285.insertOne( ...   {... details : [ ...      { ...         Name : "Chris" ...      }, ...      { ...         Name2: "Bob" ...   ... Read More
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