For conditional update, use update() and set new value using $set. Let us create a collection with documents −> db.demo150.insertOne({"StudentId":101, "StudentName":"Chris", "StudentMarks":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e350dcdfdf09dd6d08539d3") } > db.demo150.insertOne({"StudentId":102, "StudentName":"Chris", "StudentMarks":55}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e350dcefdf09dd6d08539d4") } > db.demo150.insertOne({"StudentId":103, "StudentName":"David", "StudentMarks":34}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e350dcffdf09dd6d08539d5") } > db.demo150.insertOne({"StudentId":104, "StudentName":"Chris", "StudentMarks":38}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e350dd0fdf09dd6d08539d6") }Display all documents from a collection with the help of find() method −> db.demo150.find();This will produce the following output −{ "_id" : ObjectId("5e350dcdfdf09dd6d08539d3"), "StudentId" : 101, "StudentName" ... Read More

For a case-insensitive query, use regex in MongoDB. Let us create a collection with documents −> db.demo314.insertOne({"Name":"Chris brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50d742f8647eb59e562056") } > db.demo314.insertOne({"Name":"David Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50d743f8647eb59e562057") } > db.demo314.insertOne({"Name":"CHRIS BROWN"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50d744f8647eb59e562058") } > db.demo314.insertOne({"Name":"DAVID MILLER"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50d747f8647eb59e562059") } > db.demo314.insertOne({"Name":"chris brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50d749f8647eb59e56205a") }Display all documents from a collection with the help of find() method −> db.demo314.find();This will produce the following output −{ "_id" ... Read More

Let us create a collection with documents −> db.demo313.insertOne({"_id":100, "details":[{"Name":"Chris", "Age":24}]}); { "acknowledged" : true, "insertedId" : 100 } > db.demo313.insertOne({"_id":101, "details":[{"Name":"David", "Age":22}]}); { "acknowledged" : true, "insertedId" : 101 } > db.demo313.insertOne({"_id":102, "details":[{"Name":"Mike", "Age":25}]}); { "acknowledged" : true, "insertedId" : 102 }Display all documents from a collection with the help of find() method −> db.demo313.find();This will produce the following output −{ "_id" : 100, "details" : [ { "Name" : "Chris", "Age" : 24 } ] } { "_id" : 101, "details" : [ { "Name" : "David", "Age" : 22 } ] } { "_id" : 102, "details" ... Read More

To update partial number of documents, set multi to true. Let us create a collection with documents −> db.demo312.insertOne({"FirstName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50ce16f8647eb59e56204a") } > db.demo312.insertOne({"FirstName":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50ce19f8647eb59e56204b") } > db.demo312.insertOne({"FirstName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50ce1cf8647eb59e56204c") } > db.demo312.insertOne({"FirstName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50ce20f8647eb59e56204d") } > db.demo312.insertOne({"FirstName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50ce22f8647eb59e56204e") }Display all documents from a collection with the help of find() method −> db.demo312.find();This will produce the following output −{ "_id" : ObjectId("5e50ce16f8647eb59e56204a"), "FirstName" ... Read More

For faster queries, create an index. To get the count, use count(). Let us create a collection with documents −> db.demo311.ensureIndex({"Name":1}); {    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 } > db.demo311.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50cd01f8647eb59e562044") } > db.demo311.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50cd05f8647eb59e562045") } > db.demo311.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50cd06f8647eb59e562046") } > db.demo311.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e50cd0af8647eb59e562047") } > db.demo311.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50cd0df8647eb59e562048") } > db.demo311.insertOne({"Name":"Chris"}); { ... Read More

To push document into an array, use $push along with update(). Let us create a collection with documents −>db.demo310.insertOne({"Name":"Chris", "details":[{"Id":101, "Subject":"MySQL"}, {"Id":102, "Subject":"MongoDB"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e50cabdf8647eb59e562043") }Display all documents from a collection with the help of find() method −> db.demo310.find();This will produce the following output −{    "_id" : ObjectId("5e50cabdf8647eb59e562043"), "Name" : "Chris", "details" : [       { "Id" : 101, "Subject" : "MySQL" }, { "Id" : 102, "Subject" : "MongoDB" }    ] }Following is the query to push document −> db.demo310.update({ _id:ObjectId("5e50cabdf8647eb59e562043")}, ...{ $push: {"details": { ...   "Id" ... Read More

To remove, use remove() in MongoDB. Let us create a collection with documents −> db.demo309.insertOne({ "details":[ { "Name":"Chris" }, { "Name":"David" }, { "Name":"Adam" } ] } ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4eb71af8647eb59e562040") } > db.demo309.insertOne({ "details":[ { "Name":"David" }, { "Name":"Mike" }, { "Name":"Bob" } ] } ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4eb7cbf8647eb59e562041") }Display all documents from a collection with the help of find() method −> db.demo309.find();This will produce the following output −{ "_id" : ObjectId("5e4eb71af8647eb59e562040"), "details" : [ { "Name" : "Chris" }, { "Name" : "David" }, { "Name" ... Read More

To retried a subset of fields, use dot notation in find(). Let us create a collection with documents −> db.demo307.insertOne({ ...   "CleintId":101, ...   "ClientDetails":{"ClientFirstName":"Chris", "Age":34}, ...   "ClientCountryName":"US" ...} ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4eab88f8647eb59e56203c") } > db.demo307.insertOne({ ...   "CleintId":102, ...   "ClientDetails":{"ClientFirstName":"David", "Age":31}, ...   "ClientCountryName":"UK" ...} ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4eab97f8647eb59e56203d") }Display all documents from a collection with the help of find() method −>  db.demo307.find();This will produce the following output −{ "_id" : ObjectId("5e4eab88f8647eb59e56203c"), "CleintId" : 101, "ClientDetails" : { "ClientFirstName" : "Chris", "Age" : 34 ... Read More

To fetch documents, use find() in MongoDB. With that, to format the resultant documents, use pretty().Let us create a collection with documents −> db.demo306.insertOne({"Name":"Robert", "Age":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea7c6f8647eb59e562038") } > db.demo306.insertOne({"Name":"David", "Age":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea7cdf8647eb59e562039") } > db.demo306.insertOne({"Name":"Mike", "Age":25}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea7d4f8647eb59e56203a") } > db.demo306.insertOne({"Name":"Carol", "Age":26}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea7dcf8647eb59e56203b") }Display all documents from a collection with the help of find() method −> db.demo306.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e4ea7c6f8647eb59e562038"),    "Name" : ... Read More

To get the child of a collection in MongoDB, use find(). Let us create a collection with documents −> db.demo305.insertOne( ...   { ...      _id: 101, ...      FirstName : 'Chris', ...      details : { ...         "0":"102", ...         "1":"10001" ...      } ...   } ...); { "acknowledged" : true, "insertedId" : 101 } > db.demo305.insertOne( ...   { ...      _id: 102, ...      FirstName : 'David', ...      details : { ...         "0":"103", ...         "1":"10002" ...      } ...   } ...); { "acknowledged" : true, "insertedId" : 102 }Display all documents from a collection with the help of find() method −> db.demo305.find();This will produce the following output −{ "_id" : 101, "FirstName" : "Chris", "details" : { "0" : "102", "1" : "10001" } } { "_id" : 102, "FirstName" : "David", "details" : { "0" : "103", "1" : "10002" } }Following is the query to get the child of a MongoDB collection by the key −> db.demo305.find({_id:102},{'details.0':1});This will produce the following output −{ "_id" : 102, "details" : { "0" : "103" } }