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Database Articles
Page 60 of 547
How to convert date to timestamp in MongoDB
To convert date to timestamp in MongoDB, use the $toLong operator within an aggregation pipeline. This converts an ISODate object to its Unix timestamp representation in milliseconds. Syntax db.collection.aggregate([ { $addFields: { "timestampField": { $toLong: "$dateField" } } } ]); Sample Data db.demo93.insertMany([ {"UserName": "Chris", "ArrivalDate": new ISODate("2020-10-01")}, {"UserName": ...
Read MoreFind records on or after a specific date in MongoDB?
To find records on or after a specific date in MongoDB, use the $gte (greater than or equal) operator with ISODate to perform date comparisons. Syntax db.collection.find({ "dateField": { $gte: ISODate("YYYY-MM-DD") } }); Sample Data Let us create a collection with documents containing arrival dates ? db.demo91.insertMany([ { "ArrivalDate": new ISODate("2020-01-10") }, { "ArrivalDate": new ISODate("2019-12-14") }, { "ArrivalDate": new ISODate("2020-01-15") } ]); { "acknowledged": true, ...
Read MoreMongoDB query to find documents whose array contains a string that is a substring of a specific word
To find documents whose array contains a string that is a substring of a specific word, use MongoDB's aggregation pipeline with $match, $expr, and $anyElementTrue operators combined with $indexOfBytes to check substring matches. Syntax db.collection.aggregate([ { $match: { $expr: { $anyElementTrue: { ...
Read MoreMongoDB query to get array of nested string?
To get array of nested string in MongoDB, use dot notation in find() to query nested array fields. This allows you to search for documents containing specific string values within nested arrays. Syntax db.collection.find({ "parentArray.nestedField": "searchValue" }); Sample Data db.demo89.insertMany([ { id: 101, Details: [ { Name: "Chris", Marks: 45 }, ...
Read MoreIs it possible to use MongoDB field value as a pattern in $regex?
Yes, you can use a MongoDB field value as a pattern in $regex using the $expr operator. However, the most practical approach is using $indexOfCP to check if one field value exists within another field. Syntax db.collection.aggregate([ { "$match": { "$expr": { "$ne": [ ...
Read MoreMongoDB query to exclude if id is equal to a document field array value
To exclude documents where the id field equals any value in a document's array field, use $expr with $not and $in operators. This allows field-to-field comparison within the same document. Syntax db.collection.find({ $expr: { $not: { $in: ["$idField", "$arrayField"] } } }); Sample Data Let us create a collection with documents ? db.collection.insertMany([ ...
Read MoreHow to match multiple criteria inside an array with MongoDB?
To match multiple criteria inside an array in MongoDB, use the $elemMatch operator with either find() or aggregate(). The $elemMatch operator matches documents where at least one array element satisfies all the specified criteria. Syntax db.collection.find({ "arrayField": { "$elemMatch": { "field1": "value1", "field2": "value2" } } }) ...
Read MoreMongoDB "$and" operator for subcollection to fetch a document?
When working with MongoDB subcollections (arrays of documents), use $elemMatch combined with $in or $and operators to fetch documents that match specific conditions within array elements. Syntax // Using $in for single condition db.collection.find({ "arrayField": { "$elemMatch": { "field1": "value1", "field2": { "$in": ["value2"] } } ...
Read MoreHow to make a unique field in MongoDB?
To make a unique field in MongoDB, use unique: true when creating an index. This ensures that no duplicate values can be inserted into the specified field. Syntax db.collection.createIndex( { "fieldName": 1 }, { unique: true } ); Example Let's create a unique index on the EmployeeName field ? db.demo82.createIndex({"EmployeeName":1}, {unique:true}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } ...
Read MoreFinding a specific item in subdocument with MongoDB?
To find a specific item in a subdocument in MongoDB, use dot notation to access nested fields within array elements. This allows you to query documents based on values inside subdocuments. Syntax db.collection.find({ "arrayField.nestedField": "value" }); Sample Data db.demo81.insertMany([ { "StudentDetails": [ {"StudentName": "Carol", "StudentSubject": "Java"}, {"StudentName": "David", "StudentSubject": "MongoDB"} ...
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