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MongoDB Articles
Page 79 of 111
Can MongoDB find() function display avoiding _id?
Yes, we can avoid the _id, using the following syntax in MongoDB −db.yourCollectionName.find({}, { _id:0});Let us first create a collection with documents:>> db.excludeIdDemo.insertOne({"CustomerName":"Larry"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7f62c1a844af18acdffb9") } > db.excludeIdDemo.insertOne({"CustomerName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7f6311a844af18acdffba") } > db.excludeIdDemo.insertOne({"CustomerName":"Mike"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7f6351a844af18acdffbb") } > db.excludeIdDemo.insertOne({"CustomerName":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7f6381a844af18acdffbc") }Following is the query to display all documents from a collection with the help of find() method −> db.excludeIdDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd7f62c1a844af18acdffb9"), "CustomerName" : "Larry" } ...
Read MoreHow to perform $gt on a hash in a MongoDB document?
The $gt is for greater than, wherein select those documents where the value of the field is greater than the specified value. Let us first create a collection with documents −> db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":1000, "PlayerLevel":2}, "PlayerName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7eba41a844af18acdffa9") } > db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":0, "PlayerLevel":1}, "PlayerName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ebbb1a844af18acdffaa") } > db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":-10, "PlayerLevel":0}, "PlayerName":"Larry"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ebd41a844af18acdffab") } > db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":1, "PlayerLevel":1}, "PlayerName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ebe31a844af18acdffac") }Following is the query to display all documents from a collection with the help of ...
Read MoreMongoDB query to remove array elements from a document?
Use the $pull to remove array elements from a MongoDB document as shown in the following syntax −db.yourCollectionName.update( { }, { $pull: { yourFieldName: yourValue }}, {multi:true });Let us first create a collection with documents −>db.removeArrayElementsDemo.insertOne({"AllPlayerName":["John", "Sam", "Carol", "David"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd90d011a844af18acdffc1") } >db.removeArrayElementsDemo.insertOne({"AllPlayerName":["Chris", "Robert", "John", "Mike"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd90d2e1a844af18acdffc2") }Following is the query to display all documents from a collection with the help of find() method −> db.removeArrayElementsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd90d011a844af18acdffc1"), "AllPlayerName" : [ "John", ...
Read MoreMongoDB regex to display records whose first five letters are uppercase?
Let us first create a collection with documents −> db.upperCaseFiveLetterDemo.insertOne({"StudentFullName":"JOHN Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7edef1a844af18acdffb2") } > db.upperCaseFiveLetterDemo.insertOne({"StudentFullName":"SAM Williams"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ee011a844af18acdffb3") } > db.upperCaseFiveLetterDemo.insertOne({"StudentFullName":"CAROL Taylor"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ee101a844af18acdffb4") } > db.upperCaseFiveLetterDemo.insertOne({"StudentFullName":"Bob Taylor"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ee351a844af18acdffb5") } > db.upperCaseFiveLetterDemo.insertOne({"StudentFullName":"DAVID Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7ee451a844af18acdffb6") }Following is the query to display all documents from a collection with the help of find() method −> db.upperCaseFiveLetterDemo.find().pretty();This will produce the following output −{ "_id" : ...
Read MoreHow can I update all elements in an array with a prefix string?
To update all elements in an array with a prefix string, use forEach(). Let us first create a collection with documents −> db.replaceAllElementsWithPrefixDemo.insertOne( { "StudentNames" : [ "John", "Carol" ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cd91908b50a6c6dd317ad8e") } > > > db.replaceAllElementsWithPrefixDemo.insertOne( { "StudentNames" : [ "Sam" ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cd9191cb50a6c6dd317ad8f") }Following is the query to display all documents from ...
Read MoreGet all fields names in a MongoDB collection?
You can use the concept of Map Reduce. Let us first create a collection with documents −> db.getAllFieldNamesDemo.insertOne({"StudentFirstName":"David", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ObjectId("5cd998e9b50a6c6dd317ad90") }Following is the query to display all documents from a collection with the help of find() method −> db.getAllFieldNamesDemo.find();This will produce the following output −{ "_id" : ObjectId("5cd998e9b50a6c6dd317ad90"), "StudentFirstName" : "David", "StudentAge" : 23 }Following is the query to get all fields names in a MongoDB collection −> myMapReduce = db.runCommand({ "mapreduce" : "getAllFieldNamesDemo", "map" : function() { for (var myKey in this) { emit(myKey, null); } ...
Read MoreHow to store MongoDB result in an array?
To store MongoDB result in an array, use the toArray() method −var anyVariableName=db.yourCollectionName.find().toArray();Let us first create a collection with documents −> db.mongoDbResultInArrayDemo.insertOne({"CustomerName":"David Miller", "CustomerAge":24, "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99bd5b50a6c6dd317ad92") } > db.mongoDbResultInArrayDemo.insertOne({"CustomerName":"Sam Williams", "CustomerAge":46, "isMarried":true}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99beab50a6c6dd317ad93") } > db.mongoDbResultInArrayDemo.insertOne({"CustomerName":"Carol Taylor", "CustomerAge":23, "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99bf9b50a6c6dd317ad94") }Following is the query to display all documents from a collection with the help of find() method −> db.mongoDbResultInArrayDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd99bd5b50a6c6dd317ad92"), "CustomerName" : "David Miller", "CustomerAge" ...
Read MoreI want to create a new field in an already created document. How can this be done using MongoDB query?
Use $addToSet to create a new field in MongoDB. Let us first create a collection with documents −> db.createFieldDemo.insertOne({"StudentFirstName":"John", "StudentAge":21}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99e28b50a6c6dd317ad95") } > db.createFieldDemo.insertOne({"StudentFirstName":"Larry", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99e2fb50a6c6dd317ad96") } > db.createFieldDemo.insertOne({"StudentFirstName":"Chris", "StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99e38b50a6c6dd317ad97") } > db.createFieldDemo.insertOne({"StudentFirstName":"David", "StudentAge":25}); { "acknowledged" : true, "insertedId" : ObjectId("5cd99e43b50a6c6dd317ad98") }Following is the query to display all documents from a collection with the help of find() method −> db.createFieldDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd99e28b50a6c6dd317ad95"), "StudentFirstName" : ...
Read MoreMongoDB find() to operate on recursive search?
Use find() with dot notation to perform recursive search. Let us first create a collection with documents −> db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":101, "ClientName":"Chris"}, {"ClientId":102, "ClientName":"Robert"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd9a118b50a6c6dd317ad99") } > db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":110, "ClientName":"David"}, {"ClientId":112, "ClientName":"Mike"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd9a12fb50a6c6dd317ad9a") }Following is the query to display all documents from a collection with the help of find() method −> db.findOperationDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd9a118b50a6c6dd317ad99"), "ClientDetails" : [ { "ClientId" : 101, "ClientName" : "Chris" ...
Read MoreImplement MongoDB toLowerCase() in a forEach loop to update the name of students?
Let us first create a collection with documents wherein one of the fields is StudentName −> db.lowerCaseDemo.insertOne({"StudentName":"JOHN SMith"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd9a86fb50a6c6dd317ad9f") } > db.lowerCaseDemo.insertOne({"StudentName":"CAROL TAYLor"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd9a88fb50a6c6dd317ada0") } > db.lowerCaseDemo.insertOne({"StudentName":"DAVID Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd9a89fb50a6c6dd317ada1") }Following is the query to display all documents from a collection with the help of find() method −> db.lowerCaseDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd9a86fb50a6c6dd317ad9f"), "StudentName" : "JOHN SMith" } { "_id" : ObjectId("5cd9a88fb50a6c6dd317ada0"), "StudentName" : "CAROL TAYLor" } { ...
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