Found 6702 Articles for Database

How to query with nand operator in MongoDB?

AmitDiwan
Updated on 31-Mar-2020 08:39:55

188 Views

The $not operator won’t invert a complex expression. Therefore, use $and or $or with $ne operator.Let us create a collection with documents −> db.demo266.insertOne({"active1":true, "active2":false}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480f4b1627c0c63e7dbaa7") } > db.demo266.insertOne({"active1":true, "active2":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480f501627c0c63e7dbaa8") } > db.demo266.insertOne({"active1":false, "active2":false}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480f561627c0c63e7dbaa9") } > db.demo266.insertOne({"active1":false, "active2":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480f701627c0c63e7dbaaa") }Display all documents from a collection with the help of find() method −> db.demo266.find();This will produce the following output −{ "_id" : ObjectId("5e480f4b1627c0c63e7dbaa7"), "active1" : true, "active2" ... Read More

MongoDB query to update only certain fields?

AmitDiwan
Updated on 31-Mar-2020 08:37:55

178 Views

To update only certain fields, use $set. Let us create a collection with documents −> db.demo265.insertOne({"id":101, "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480d781627c0c63e7dbaa4") } > db.demo265.insertOne({"id":102, "Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480d7d1627c0c63e7dbaa5") } > db.demo265.insertOne({"id":103, "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e480d841627c0c63e7dbaa6") }Display all documents from a collection with the help of find() method −> db.demo265.find();This will produce the following output −{ "_id" : ObjectId("5e480d781627c0c63e7dbaa4"), "id" : 101, "Name" : "Chris" } { "_id" : ObjectId("5e480d7d1627c0c63e7dbaa5"), "id" : 102, "Name" : "Bob" } { "_id" : ObjectId("5e480d841627c0c63e7dbaa6"), "id" : 103, ... Read More

Using count equivalent in MongoDB to find top users with max occurrence

AmitDiwan
Updated on 31-Mar-2020 08:36:07

381 Views

To get the count and top users, use $group along with aggregate() . Let us create a collection with documents −> db.demo264.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed441627c0c63e7dba9e") } > db.demo264.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed471627c0c63e7dba9f") } > db.demo264.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed491627c0c63e7dbaa0") } > db.demo264.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed4c1627c0c63e7dbaa1") } > db.demo264.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed4e1627c0c63e7dbaa2") } > db.demo264.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e47ed531627c0c63e7dbaa3") }Display all documents from a collection with the help ... Read More

MongoDB query to skip documents

AmitDiwan
Updated on 31-Mar-2020 08:34:31

174 Views

To skip documents in MongoDB, use skip(). Let us create a collection with documents −> db.demo263.insertOne({_id:100}); { "acknowledged" : true, "insertedId" : 100 } > db.demo263.insertOne({_id:200}); { "acknowledged" : true, "insertedId" : 200 } > db.demo263.insertOne({_id:300}); { "acknowledged" : true, "insertedId" : 300 }Display all documents from a collection with the help of find() method −> db.demo263.find();This will produce the following output −{ "_id" : 100 } { "_id" : 200 } { "_id" : 300 }Following is the query to skip document −> result = db.demo263.aggregate([ ...   { ...      $project: { ...         v_id: { $ifNull: [null, [100, 200]] } ... ...      } ...   }, ...   { $unwind: '$v_id' }, ...   { $sort: { v_id: 1, _id: 1 } }, ... ...   { $skip: 2 }, ...   { $limit: 2 } ...]);This will produce the following output −{ "_id" : 300, "v_id" : 100 } { "_id" : 100, "v_id" : 200 }

Invert Result of MongoDB Query (Implement Opposite of $and operation)?

AmitDiwan
Updated on 31-Mar-2020 08:33:54

194 Views

To invert result i.e. opposite of $and operation, use $OR along with $ne. Let us first create a collection with documents −> db.demo4.insert({uid:1, "Name":"Chris", "Age":22}); WriteResult({ "nInserted" : 1 }) > db.demo4.insert({uid:2, "Name":"David", "Age":21}); WriteResult({ "nInserted" : 1 }) > db.demo4.insert({uid:3, "Name":"Bob", "Age":23}); WriteResult({ "nInserted" : 1 }) > db.demo4.insert({uid:1, "Name":"Carol", "Age":20}); WriteResult({ "nInserted" : 1 })Following is the query to display all documents from a collection with the help of find() method −> db.demo4.find();This will produce the following output −{ "_id" : ObjectId("5e0a1da125ddae1f53b62221"), "uid" : 1, "Name" : "Chris", "Age" : 22 } { "_id" : ObjectId("5e0a1db025ddae1f53b62222"), "uid" : ... Read More

Modify sequence in MongoDB

AmitDiwan
Updated on 31-Mar-2020 08:32:23

247 Views

To modify a sequence, use findAndModify(). Let us create a collection with documents −> db.demo261.insertOne({_id:100, Name:"Chris"}); { "acknowledged" : true, "insertedId" : 100 }Display all documents from a collection with the help of find() method −> db.demo261.find();This will produce the following output −{ "_id" : 100, "Name" : "Chris" }Following is the query to modify sequence −> db.demo262.insert({_id:"newId", sequence_value:0}) WriteResult({ "nInserted" : 1 }) > function getNext(sName){ ... ...   var d= db.demo262.findAndModify({ ...      query:{_id: sName}, ...      update: {$inc:{sequence_value:1}}, ...      new:true ...   }); ...   return d.sequence_value; ...}Following is the query to call ... Read More

Script to add a single value to array in MongoDB collection?

AmitDiwan
Updated on 31-Mar-2020 08:32:32

179 Views

To add only a single value to array, use $push. Let us first create a collection with documents −> db.demo3.insertOne( ...    { ...       "Information" : { ...          "Of" : { ...             "StudentCode" : "STUDENT101", ...             "StudentFavouriteSubject" : [ ...                "MySQL", ...                "Java" ...             ] ...          } ...       } ...    } ... ); ... Read More

Get MongoDB documents that contains specific attributes in array

AmitDiwan
Updated on 31-Mar-2020 08:29:26

449 Views

For this, you can use $and along with dot(.) notation. Let us first create a collection with documents −>db.demo2.insertOne({"StudentInformation":[{"StudentName":"John", "StudentAge":21}, {"StudentName":"Mike", "StudentAge":22}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e08b56e25ddae1f53b62219") } >db.demo2.insertOne({"StudentInformation":[{"StudentName":"Carol", "StudentAge":19}, {"StudentName":"Bob", "StudentAge":18}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e08b58625ddae1f53b6221a") }Following is the query to display all documents from a collection with the help of find() method −> db.demo2.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e08b56e25ddae1f53b62219"),    "StudentInformation" : [       {          "StudentName" : "John",          "StudentAge" : 21       }, ... Read More

How to run MongoDB shell using mongos command?

AmitDiwan
Updated on 31-Mar-2020 08:26:14

687 Views

In order to launch the MongoDB shell, you need to use mongo command. Following is the syntax −>mongoFirst reach the MongoDB bin directory from command prompt as in the below screenshot −Here is the command to launch the mongo shell as in the below screenshot −This will produce the following output −

How to update % printed to Console from MongoDB?

AmitDiwan
Updated on 31-Mar-2020 08:24:16

85 Views

To update and print to console from MongoDB script, create a variable and then use the print() method.Let us first create a variable −> var amount=10.58945;Here is the query to update % printed to console −> var amount=10.58945; > print(amount.toFixed(2)+" %");This will produce the following output −10.59 %

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