To understand the query with an or condition, let us create a collection with the document. The query to create a collection with a document is as follows −> db.orConditionDemo.insertOne({"CustomerName":"Larry", "ShippingDate":new ISODate("2018-01-29")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ec5262f684a30fbdfd56a") } > db.orConditionDemo.insertOne({"CustomerName":"Mike", "ShippingDate":new ISODate("2019-04-13")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ec5362f684a30fbdfd56b") } > db.orConditionDemo.insertOne({"CustomerName":"Bob", "ShippingDate":new ISODate("2019-02-21")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ec5422f684a30fbdfd56c") } > db.orConditionDemo.insertOne({"CustomerName":"David", "ShippingDate":new ISODate("2019-03-15")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ec5532f684a30fbdfd56d") } > db.orConditionDemo.insertOne({"CustomerName":"John", "ShippingDate":new ISODate("2019-03-19")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ec56c2f684a30fbdfd56e") }Display all documents ... Read More

You can return a specific field from collection.find() by using the following syntax.Case 1 − The syntax is as follows −db.yourCollectionName.find({}, {"yourFieldName":1}).pretty();The above field name is set to 1 means it will return only that field. If you set to 0 it will return all fields except the field which is set to 0.Case 2 − The syntax is as follows −db.yourCollectionName.find({}, {"yourFieldName":0}).pretty();To understand the above syntaxes, let us create a collection with document. The query to create a collection with document is as follows −> db.returnFieldInFindDemo.insertOne({"StudentName":"John", "StudentAge":23, "TechnicalSubject":["MongoDB", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ebfe72f684a30fbdfd566") } ... Read More

You can use ensureIndex() to boost the performance of count() method in MongoDB. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.countPerformanceDemo.insertOne({"StudentName":"John", "StudentCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ebcf82f684a30fbdfd55f") } > db.countPerformanceDemo.insertOne({"StudentName":"Mike", "StudentCountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ebd042f684a30fbdfd560") } > db.countPerformanceDemo.insertOne({"StudentName":"David", "StudentCountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ebd112f684a30fbdfd561") } > db.countPerformanceDemo.insertOne({"StudentName":"Carol", "StudentCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ebd1a2f684a30fbdfd562") } > db.countPerformanceDemo.insertOne({"StudentName":"Bob", "StudentCountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ... Read More

You can use $set operator for this. The syntax is as follows −db.yourCollectionName.update({ }, {'$set': "yourFieldName": "yourValue" }, false, true);To understand the above syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Larry", "ClientAge":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8eb7372f684a30fbdfd557") } > db.unconditionalUpdatesDemo.insertOne({"ClientName":"Mike", "ClientAge":26}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8eb73f2f684a30fbdfd558") } > db.unconditionalUpdatesDemo.insertOne({"ClientName":"Sam", "ClientAge":27}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8eb7462f684a30fbdfd559") } > db.unconditionalUpdatesDemo.insertOne({"ClientName":"Carol", "ClientAge":29}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8eb7502f684a30fbdfd55a") }Display all documents from a ... Read More

You can restrict case insensitive search in MongoDB with the help of '$regex'. The syntax is as follows −db.yourCollectionName.find({"yourFieldName" : { '$regex':'^yourValue$'}});You can use another regex. The syntax is as follows −db.yourCollectionName.find({"Name" : { '$regex':/^yourValue$/i}});To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.caseInsesitiveDemo.insertOne({"Name":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bd66293c80e3f23815e83") } > db.caseInsesitiveDemo.insertOne({"Name":"Johnson"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bd66693c80e3f23815e84") } > db.caseInsesitiveDemo.insertOne({"Name":"Johny"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bd66a93c80e3f23815e85") }Display all documents from a collection with ... Read More

To write on console, you need to use print() method. The syntax is as follows −print(“yourString”);To display objects, you can use printjson(). The syntax is as follows −printjson(yourObjectName);Let us implement both the functions. The first query is as follows to display something −> print("Welcome to MongoDB Console");The following is the output on a console −Welcome to MongoDB ConsoleLet us create an object. The query is as follows −>studentInformation={"StudentName":"John", "StudentAge":24, "StudentTechnicalSkills":["C", "C++", "Java", "MongoDB", "MySQL"]}; {    "StudentName" : "John",    "StudentAge" : 24,    "StudentTechnicalSkills" : [       "C",       "C++",       "Java",     ... Read More

To clone a collection in MongoDB, you can use the forEach() method. Let us first create a collection with a document.The query to create a collection with a document is as follows −> db.studentInformation.insertOne({"StudentName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bc15780f10143d8431e21") } > db.studentInformation.insertOne({"StudentName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bc15e80f10143d8431e22") } > db.studentInformation.insertOne({"StudentName":"James"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bc17380f10143d8431e23") }Display all documents from a collection with the help of find() method. The query is as follows −> db.studentInformation.find().pretty();The following is the output −{ "_id" : ObjectId("5c8bc15780f10143d8431e21"), "StudentName" : "Chris" } { "_id" ... Read More

To get the element with a max id, you can use the find() method. To understand the above concept, let us create a collection with the document. The query is as follows −> db.getElementWithMaxIdDemo.insertOne({"Name":"John", "Age":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bbce480f10143d8431e1c") } > db.getElementWithMaxIdDemo.insertOne({"Name":"Larry", "Age":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bbcec80f10143d8431e1d") } > db.getElementWithMaxIdDemo.insertOne({"Name":"David", "Age":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bbcf580f10143d8431e1e") } > db.getElementWithMaxIdDemo.insertOne({"Name":"Chris", "Age":20}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bbcfe80f10143d8431e1f") } > db.getElementWithMaxIdDemo.insertOne({"Name":"Robert", "Age":25}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8bbd0880f10143d8431e20") }Display all documents from ... Read More

To rename a collection in MongoDB, you can use renameCollection() method. The syntax is as follows −db.yourOldCollectionName.renameCollection('yourNewCollectionName');To understand the above syntax, let us list all the collections from database sample. The query is as follows −> use sample; switched to db sample > show collections;The following is the output −copyThisCollectionToSampleDatabaseDemo deleteDocuments deleteDocumentsDemo employee informationAboutDelete internalArraySizeDemo prettyDemo selectWhereInDemo sourceCollection updateInformation userInformationNow change collection name ‘informationAboutDelete’ to ‘deleteSomeInformation’. The query is as follows to change the collection name.> db.informationAboutDelete.renameCollection('deleteSomeInformation'); { "ok" : 1 }Here is the query to check the collection name has been renamed to 'deleteSomeInformation' −> show collections;The following is ... Read More

To aggregate sum in MongoDB to get the total count, you can use the $sum operator. To understand the above concept, let us create a collection with the document −> db.aggregateSumDemo.insertOne({"CustomerName":"Larry", "Amount":140}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8baa0680f10143d8431e18") } > db.aggregateSumDemo.insertOne({"CustomerName":"Mike", "Amount":160}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8baa1380f10143d8431e19") } > db.aggregateSumDemo.insertOne({"CustomerName":"Sam", "Amount":300}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8baa1c80f10143d8431e1a") } > db.aggregateSumDemo.insertOne({"CustomerName":"David", "Amount":500}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8baa2580f10143d8431e1b") }Display all documents from a collection with the help of find() method. The query is as follows −> db.aggregateSumDemo.find().pretty();The following ... Read More