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To retrieve array values from a find query, use dot notation. Let us create a collection with documents −> db.demo38.insertOne({"ClientDetails":[{"ClientId":101, "ClientName":"Chris"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e176abccfb11e5c34d898d9") } > db.demo38.insertOne({"ClientDetails":[{"ClientId":102, "ClientName":"David"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e176ac7cfb11e5c34d898da") } > db.demo38.insertOne({"ClientDetails":[{"ClientId":103, "ClientName":"Mike"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e176ad0cfb11e5c34d898db") }Display all documents from a collection with the help of find() method −> db.demo38.find();This will produce the following output −{ "_id" : ObjectId("5e176abccfb11e5c34d898d9"), "ClientDetails" : [ { "ClientId" : 101, "ClientName" : "Chris" } ] } { "_id" : ObjectId("5e176ac7cfb11e5c34d898da"), "ClientDetails" : [ { ... Read More
REPL stands for Read-Evaluate-Print-Loop. It holds some states, and each statement in JShell has a state. This state denies the execution status of snippets and variables. It can be determined by the results of the eval() method of JShell instance, which evaluates the code.There are seven different status states listed below.DROPPED: The snippet is inactive.NONEXISTENT: The snippet is inactive because it does not yet exist.OVERWRITTEN: The snippet is inactive because it has been replaced by a new snippet.RECOVERABLE_DEFINED: The snippet is a declaration snippet with potentially recoverable unresolved references or other issues in its body.RECOVERABLE_NOT_DEFINED: The snippet is a declaration snippet with ... Read More
To convert string to int, use parseInt() in MongoDB. Let us first create a collection with documents −> db.demo369.insertOne({"Price":"1000000"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e2e32ae06a1609a00aed") } > db.demo369.insertOne({"Price":"1747864"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e2e92ae06a1609a00aee") } > db.demo369.insertOne({"Price":"19548575"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e2ee2ae06a1609a00aef") }Display all documents from a collection with the help of find() method −> db.demo369.find();This will produce the following output −{ "_id" : ObjectId("5e57e2e32ae06a1609a00aed"), "Price" : "1000000" } { "_id" : ObjectId("5e57e2e92ae06a1609a00aee"), "Price" : "1747864" } { "_id" : ObjectId("5e57e2ee2ae06a1609a00aef"), "Price" : "19548575" }Following is the query to convert ... Read More
To select a specific subdocument in MongoDB, use find(). Let us create a collection with documents −> db.demo37.insertOne({"Details":[{"Name":"Chris", "Age":21}, {"Name":"David", "Age":23}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e176635cfb11e5c34d898d7") } > db.demo37.insertOne({"Details":[{"Name":"Sam", "Age":23}, {"Name":"Robert", "Age":25}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e17664acfb11e5c34d898d8") }Display all documents from a collection with the help of find() method −> db.demo37.find();This will produce the following output −{ "_id" : ObjectId("5e176635cfb11e5c34d898d7"), "Details" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "David", "Age" : 23 } ] } { "_id" : ObjectId("5e17664acfb11e5c34d898d8"), "Details" : [ { "Name" : "Sam", ... Read More
At first, let us create a collection with letters and numbers, for example −7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368Access the above collection using db.getCollection(). Let us now create a collection with the name mentioned above −> db.createCollection('7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368'); { "ok" : 1 } >db.getCollection('7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368').insertOne({"FirstName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e2152ae06a1609a00aea") } >db.getCollection('7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368').insertOne({"FirstName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e21a2ae06a1609a00aeb") } >db.getCollection('7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368').insertOne({"FirstName":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e57e21e2ae06a1609a00aec") }Display all documents from a collection with the help of find() method −> db.getCollection('7664734-541d-r5i5f-845575e-ghfhjrjr3747_demo368').find();This will produce the following output −{ "_id" : ObjectId("5e57e2152ae06a1609a00aea"), "FirstName" : "Chris" } { "_id" : ObjectId("5e57e21a2ae06a1609a00aeb"), ... Read More
To find on the basis of true or false values, use $exists in find(). You would also need dot notation for the same task.Let us first create a collection with documents −> db.demo367.insertOne( ... { "Id" : "102", ... "details" : [ { "Name" : "David"}, ... { "Age" : 23, "CountryName" : "UK"} ], ... "isMarried" : false } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e57e0b62ae06a1609a00ae8") } > db.demo367.insertOne( ... { "Id" : "101", ... "details" : [ { "Name" : "Chris", "Subject" : [ "MySQL" ] }, ... ... Read More
To get distinct values, use MongoDB DISTINCT. For length, use LENGTH(). Let us create a collection with documents −> db.demo36.insertOne({"Names":["Chris", "Bob"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e17643bcfb11e5c34d898d4") } > db.demo36.insertOne({"Names":["Mike", "Sam", "Carol"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e176449cfb11e5c34d898d5") } > db.demo36.insertOne({"Names":["Chris", "Bob", "David"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e17645bcfb11e5c34d898d6") }Display all documents from a collection with the help of find() method −> db.demo36.find();This will produce the following output −{ "_id" : ObjectId("5e17643bcfb11e5c34d898d4"), "Names" : [ "Chris", "Bob" ] } { "_id" : ObjectId("5e176449cfb11e5c34d898d5"), "Names" : [ "Mike", "Sam", "Carol" ] } ... Read More
To ignore NULL and UNDEFINED values, use $ne in MongoDB. Let us create a collection with documents −> db.demo35.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e175e42cfb11e5c34d898d0") } > db.demo35.insertOne({"Name":null}); { "acknowledged" : true, 9 "insertedId" : ObjectId("5e175e46cfb11e5c34d898d1") } > db.demo35.insertOne({"Name":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e175e4bcfb11e5c34d898d2") } > db.demo35.insertOne({"Name":undefined}); { "acknowledged" : true, "insertedId" : ObjectId("5e175e54cfb11e5c34d898d3") }Display all documents from a collection with the help of find() method −> db.demo35.find();This will produce the following output −{ "_id" : ObjectId("5e175e42cfb11e5c34d898d0"), "Name" : "Chris" } { "_id" : ObjectId("5e175e46cfb11e5c34d898d1"), "Name" : null } ... Read More
To compare attributes, use $let along with $indexOfArray. Let us first create a collection with documents −> db.demo366.insertOne( ... { ... ... "Name" : "Chris", ... "details" : [ ... { ... "Id" : "John1", ... "value" : "test" ... }, ... { ... "Id" : "John2", ... "value" : 18 ... }, ... { ... "Id" : ... Read More
Use UPDATE to update and SET to set the new values. Let us create a collection with documents −> db.demo34.insertOne({"StudentFirstName":"Chris", "StudentAge":24}); { "acknowledged" : true, "insertedId" : ObjectId("5e1758b4cfb11e5c34d898cd") } > db.demo34.insertOne({"StudentFirstName":"David", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ObjectId("5e1758bdcfb11e5c34d898ce") } > db.demo34.insertOne({"StudentFirstName":"Bob", "StudentAge":20}); { "acknowledged" : true, "insertedId" : ObjectId("5e1758c6cfb11e5c34d898cf") }Display all documents from a collection with the help of find() method −> db.demo34.find();This will produce the following output −{ "_id" : ObjectId("5e1758b4cfb11e5c34d898cd"), "StudentFirstName" : "Chris", "StudentAge" : 24 } { "_id" : ObjectId("5e1758bdcfb11e5c34d898ce"), "StudentFirstName" : "David", "StudentAge" : 23 } { "_id" : ... Read More