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Found 1659 Articles for Big Data Analytics
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
499 Views
For this, use $indexOfArray. Let us first create a collection with documents −> db.demo381.insertOne({"Values":[10, 40, 60, 30, 60]}); { "acknowledged" : true, "insertedId" : ObjectId("5e5b59f72ae06a1609a00b15") } > db.demo381.insertOne({"Values":[100, 500, 700, 500, 800]}); { "acknowledged" : true, "insertedId" : ObjectId("5e5b59f72ae06a1609a00b16") } > db.demo381.insertOne({"Values":[20, 40, 30, 10, 60]}); { "acknowledged" : true, "insertedId" : ObjectId("5e5b59f72ae06a1609a00b17") }Display all documents from a collection with the help of find() method −> db.demo381.find();This will produce the following output −{ "_id" : ObjectId("5e5b59f72ae06a1609a00b15"), "Values" : [ 10, 40, 60, 30, 60 ] } { "_id" : ObjectId("5e5b59f72ae06a1609a00b16"), "Values" : [ 100, ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
962 Views
The $addToSet operator adds a value to an array unless the value is already present, in which case $addToSet does nothing to that array.Let us first create a collection with documents −> db.demo380.insertOne({ ... ... "details" : [ ... { ... "Name" : "Chris", ... "details1" : [ ] ... }, ... { ... "Name" : "David", ... "details1" : [ ] ... } ... ] ... } ... ); ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
929 Views
For projection on specific nested properties, use aggregate() in MongoDB. Let us first create a collection with documents −> db.demo379.insertOne( ... { ... "details1" : { ... "details2" : { ... "details3" : { ... "10" : "John", ... "50" : "Chris", ... "40" : "David", ... "30":"Mike" ... } ... ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
144 Views
To manipulate subdocuments, use dot(.) notation in MongoDB. Let us first create a collection with documents −> db.demo378.insertOne( ... { ... Name: 'Chris', ... details:[ ... {id:101, Score:56}, ... {id:102, Score:78} ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e5a758a2ae06a1609a00b0f") }Display all documents from a collection with the help of find() method −> db.demo378.find();This will produce the following output −{ "_id" : ObjectId("5e5a758a2ae06a1609a00b0f"), "Name" : "Chris", "details" : [ { "id" ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
314 Views
To concatenate, use $concat in MongoDB aggregate(). Let us first create a collection with documents −> db.demo377.insertOne({"ListOfIds":[1001, 1002, 1003, 1004, 1005, 1006, 1007]}); { "acknowledged" : true, "insertedId" : ObjectId("5e5a73462ae06a1609a00b0e") }Display all documents from a collection with the help of find() method −> db.demo377.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e5a73462ae06a1609a00b0e"), "ListOfIds" : [ 1001, 1002, 1003, 1004, 1005, 1006, 1007 ] }Following is the query to concatenate an array of integer ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
573 Views
To update documents, you cannot use aggregation pipeline. You can use update(). Let us first create a collection with documents −> db.demo376.insertOne( ... { ... ... "id" :101, ... ... "details" : [ ... { ... Name:"Chris", ... Age:21, ... Score:45 ... }, ... { ... Name:"David", ... Age:23, ... ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
481 Views
JavaScript function can be saved for reuse using a system collection called system.js. To store a function, use the db.collection.save(),Let us first create a function. Following is the query −> db.system.js.save({ ... _id: "displayMessage", ... value: function (data) { ... return 'The Name is: ' + data; ... } ... })This will produce the following output −WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : "displayMessage" })Following is the query to execute stored function −> db.eval("displayMessage('John')") WARNING: db.eval is deprecatedThis will produce the following output −The Name is: John
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
233 Views
There is no difference between show dbs and show databases. Both commands internally call listDatabases command.The show dbs command is as follows −> show dbsThis will produce the following output −admin 0.002GB app 0.000GB business 0.000GB config 0.000GB local 0.000GB main 0.000GB ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
506 Views
To find when the keys are unknown, use $addField and $objectToArray. Let us first create a collection with documents −> db.demo375.insertOne( ... { ... "details":{ ... "Name":"John", ... "Age":23 ... } ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e5a0ae42ae06a1609a00b06") } > db.demo375.insertOne( ... { ... "details":{ ... "Name":"David", ... "Age":21 ... } ... } ... ); { "acknowledged" : true, "insertedId" ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
385 Views
To group by another field, use $group along with $project. Let us first create a collection with documents −> db.demo374.insertOne( ... { ... ... "Name" : "Chris", ... "HobbyDetails" : [ ... "Reading Book", ... "Playing Football" ... ], ... "CountryName" : "US" ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e5a04402ae06a1609a00b04") } > db.demo374.insertOne( ... { ... ... "Name" : "Chris", ... "HobbyDetails" : [ ... ... Read More