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In MongoDB, the data records are stored as BSON documents. Here, BSON stands for binary representation of JSON documents, although BSON contains more data types as compared to JSON. The document is created using field-value pairs or key-value pairs and the value of the field can be of any BSON type.

In MongoDB, the $set operator is used to replace the value of a field to the specified value. If the given field does not exist in the document, the $set operator will add the field to the specified value. Our database name is 'myinfo' and our collection name is "employee".

$set outputs documents that contain all existing fields from the input documents and newly added fields. The $set stage is an alias for $addFields . Both stages are equivalent to a $project stage that explicitly specifies all existing fields in the input documents and adds the new fields.

Group of documents that are published together, and where the items all refer to each other by name or link. Note 1: Republishing or bundling previously published documents as a collection does not constitute a set of documents.

The MongoDB shell provides the following methods to insert documents into a collection: To insert a single document, use db. collection. insertOne() . To insert multiple documents, use db. collection. insertMany() .

The $set operator replaces the value of a field with the specified value. The $set operator expression has the following form: { $set: { <field1>: <value1>, ... } } To specify a <field> in an embedded document or in an array, use dot notation.

To assign a variable, specify a string for the variable name and assign a valid expression for the value. The variable assignments have no meaning outside the in expression, not even within the vars block itself. The expression to evaluate.