For such evaluations, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo90.insertOne( ... {"words": ["john", "jace"] ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2c1ada79799acab037af56") } > db.demo90.insertOne( ... {"words": ["sam", "adam"] ... } ... ); {    "acknowledged" : true,   ... Read More

To get array of nested string in MongoDB, use dot notation in find(). Let us create a collection with documents −> db.demo89.insertOne( ... { id: 101, Details: [ { Name: "Chris", Marks: 45 }, { Name: "David", Marks: 55, Subjects : ["MySQL", "MongoDB", "Java", "C"] } ] ... } ... ... Read More

Yes, you can use $indexOfCP to use a filed value as a pattern. Let us create a collection with documents −> db.demo88.insertOne( ...    { ...       "Name": "Chris", ...       "PassoutYear": "2020", ...       "websiteName": "chris.shop.com/Carol-2020-" ...    } ... ); {   ... Read More

To filter by several array elements, use $elemMatch. Let us create a collection with documents −> db.demo87.insertOne( ...    { ...       id:101, ...       "Details": [ ...          { ...             "EmployeeName": "Chris", ...       ... Read More

For this, use $not along with $in. Let us create a collection with documents −[    {       id: "101",       subjectid: [          "102"       ]    },    {       id: "102",       subjectid: [ ... Read More

To match multiple criteria inside an array, use aggregate(). Let us create a collection with documents −> db.demo84.insertOne({ ...    "EmployeeDetails": [ ...       {Name: 'John', Salary:45000, isMarried: true}, ...       {Name: 'Chris', Salary:50000, isMarried: false} ...       ] ...    } ... ); ... Read More

To fetch a document, use $in, instead of $and in MongoDB. Let us first create a collection with documents −> db.demo83.insertOne( ... { ...    "Details":[ ...       { ...          "Name":"Chris", ...          "Subject":[ ...             ... Read More

To make a unique field in MongoDB, use unique − true. Let us create a collection with documents −> db.demo82.createIndex({"EmployeeName":1}, {unique:true}); {    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 } > db.demo82.insertOne({"EmployeeName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2bfb1b71bf0181ecc422a0") ... Read More

To get a specific item in a sudocument, use the dot(.) notation. Let us create a collection with documents −> db.demo81.insertOne({"StudentDetails":[{"StudentName":"Carol", "StudentSubject":"Java"}, { "StudentName" : "David", "StudentSubject" : "MongoDB" }]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2bf6ec71bf0181ecc4229d") } > db.demo81.insertOne({"StudentDetails":[{"StudentName":"Mike", "StudentSubject":"Python"}, { "StudentName" : "David", "StudentSubject" : "C" ... Read More

To calculate average in MongoDB, use $avg. Let us create a collection with documents −> db.demo80.insertOne({"Details":{"Price":10.5}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2bf43271bf0181ecc42297") } > db.demo80.insertOne({"Details":{"Price":50.3}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2bf43871bf0181ecc42298") } > db.demo80.insertOne({"Details":{"Price":100.10}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2bf43f71bf0181ecc42299") }Display ... Read More