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MongoDB Articles
Page 11 of 111
How do I sort natural in MongoDB?
Use $natural to sort documents in MongoDB by their natural order (the order they were inserted into the database). This operator sorts documents based on their physical storage order on disk. Syntax db.collection.find().sort({ $natural: 1 }) // Ascending (insertion order) db.collection.find().sort({ $natural: -1 }) // Descending (reverse insertion order) Sample Data Let us create a collection with documents ? db.demo684.insertMany([ {Value: 10}, {Value: 50}, {Value: 60}, {Value: 40} ]); ...
Read MoreWhat happens when we try to add a number to undefined value?
If you try to add a number to an undefined value, you will get NaN (Not a Number). This happens because JavaScript cannot perform mathematical operations when one operand is undefined. Understanding NaN NaN stands for "Not a Number" and is returned when a mathematical operation cannot produce a meaningful numeric result. When you add a number to undefined, JavaScript attempts type coercion but fails, resulting in NaN. Case 1: Direct Addition with Undefined Here's what happens when you directly add a number to undefined ? var result = 10 + undefined; console.log(result); console.log(typeof ...
Read MoreCount the documents with a field value beginning with 13
To count documents where a field value begins with "13", use MongoDB's $regex operator with the ^ anchor for pattern matching, combined with the count() method for efficient counting. Syntax db.collection.count({ "fieldName": { "$regex": "^13" } }); Sample Data db.demo570.insertMany([ {Information: {Value: "13675"}}, {Information: {Value: "14135"}}, {Information: {Value: "15113"}}, {Information: {Value: "13141"}} ]); { "acknowledged": true, "insertedIds": [ ...
Read MoreMongoDB query to match documents whose _id is in an array as part of a subdocument?
To match documents whose _id is in an array stored as part of a subdocument, use the $in operator combined with distinct() to extract array values from the subdocument field. Syntax db.targetCollection.find({ "_id": { "$in": db.sourceCollection.distinct("arrayField.subField", {filter}) } }); Sample Data Create a collection with an array of subdocuments containing IDs ? db.demo568.insertOne({ _id: 101, details: [ { id: 101 }, ...
Read MoreMongoDB collection query to exclude some fields in find()?
To exclude specific fields from MongoDB query results, set the unwanted fields to 0 in the projection parameter of the find() method. This allows you to retrieve documents while hiding sensitive or unnecessary data. Syntax db.collectionName.find( { query }, { fieldToExclude1: 0, fieldToExclude2: 0 } ); Sample Data db.demo567.insertMany([ { "Name": "Chris", "Age": 21 }, { "Name": "David", "Age": 23 }, { "Name": "Bob", "Age": 22 }, { "Name": ...
Read MoreGrouping the array items in MongoDB and get the count the products with similar price?
To group array items in MongoDB and count products with similar prices, use the $unwind operator to flatten the array, then $group by price and $sum to count occurrences. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $group: { "_id": "$arrayField.fieldToGroupBy", "count": { $sum: 1 } }}, { $sort: { "_id": 1 } } ]) Sample Data db.products.insertOne({ ...
Read MoreMongoDB - how can I access fields in a document?
To access fields in a MongoDB document, use the find() method with optional field projection to specify which fields to return. You can access all fields or select specific ones using projection syntax. Syntax // Access all fields db.collection.find(query); // Access specific fields using projection db.collection.find(query, {field1: 1, field2: 1, _id: 0}); Sample Data db.demo565.insertMany([ { id: 101, Name: "David", CountryName: "US" ...
Read MoreMake MongoDB replace single array value with string?
To replace a single array value with a string in MongoDB, use the $set operator combined with the positional operator $. The positional operator identifies the array element that matches the query condition and allows you to update it. Syntax db.collection.updateMany( { "arrayField": "valueToMatch" }, { "$set": { "arrayField.$": "newValue" } } ); Sample Data db.demo564.insertOne({ "StudentName": ["Chris", "David", "Mike", "Sam"] }); { "acknowledged": true, "insertedId": ObjectId("5e90880a39cfeaaf0b97b576") } ...
Read MoreHow to get items with a specific value from documents using MongoDB shell?
To get documents with a specific field value in MongoDB, use the find() method with a query filter. This allows you to retrieve only the documents that match your specified criteria. Syntax db.collection.find( { "field": "value" }, { "field1": 1, "field2": 1 } ) The first parameter is the query filter, and the second optional parameter is the projection to specify which fields to include or exclude. Sample Data db.demo563.insertMany([ { "Name": "Chris", "Age": 21, "isMarried": true }, ...
Read MoreHow to search for a record (field) and then delete it in MongoDB?
To search for a field and then delete it in MongoDB, use $exists to find documents containing the field, then $unset to remove it. The $unset operator deletes a particular field from documents. Syntax db.collection.update( { "fieldName": { $exists: true } }, { $unset: { "fieldName": "" } }, { multi: true } ); Sample Data Let us create a collection with documents ? db.demo562.insertMany([ { "Name": "Chris", "Age": 21 }, { ...
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