How are subfields accessed in MongoDB queries?

In MongoDB queries, subfields are accessed using dot notation, which allows you to navigate through documents and access nested fields. For instance, if you have a document with a structure like { "user": { "name": "Alice", "age": 30 } }, you can access the name field by using the query user.name.

While quotation marks are typically used around field names when they contain special characters or spaces, using quotation marks is not required for simple subfields when they are queried with dot notation in most situations. Thus, relying solely on dot notation without the need for extra quotation marks is both standard and sufficient for accessing these nested fields in most cases, simplifying your query syntax and reducing potential errors.

This makes the first option the most effective method for querying nested data structures, and it’s crucial to keep in mind that, while surrounding field names with quotation marks can sometimes be valid for certain scenarios, it is generally not the standard practice for subfields. Therefore, understanding that dot notation is the primary and most commonly used approach to access subfields is essential for effectively querying in MongoDB.