$nor Operator - (MongoDB Misc)

MongoDB's $nor operator is an important query operator that allows you to search for documents that don't match any of the specified conditions. In this page, we will discuss the syntax, examples, and applications of the $nor operator.

Syntax

The $nor operator is used to find documents that don't match any of the given conditions. Here is the syntax for the $nor operator:

{ $nor: [ { <expression1> }, { <expression2> }, ... , { <expressionN> } ] }

Here, <expression> represents any valid expression that can evaluate to a Boolean value.

Example

Consider a collection of books and their authors. Here's an example of a query that matches all books whose author isn't "J. K. Rowling" or "George R. R. Martin":

db.books.find( { $nor: [ { author: "J. K. Rowling" }, { author: "George R. R. Martin" } ] } )

This query returns all books whose author isn't "J. K. Rowling" or "George R. R. Martin".

Output

The results of a $nor query are all the documents that don't match any of the specified conditions.

Explanation

The $nor operator in MongoDB provides a way to find documents that don't match any of the specified conditions. This can be useful in cases where you want to find documents that match none of two or more conditions.

When you use the $nor operator in a query, MongoDB searches for documents that do not match any of the specified conditions inside the $nor expression.

Use

You can use the $nor operator to select documents that don't match any of the specified conditions. For example, you can use it to exclude documents that match certain criteria or to narrow down a list of documents that meet specific criteria.

Important Points

• The $nor operator matches documents that don't match any of the specified conditions.
• You can specify any number of conditions inside the $nor expression.
• You can use the $nor operator with other query operators to create complex queries.

Summary

In this page, we discussed the syntax, example, output, explanation, use, and important points of the $nor operator in MongoDB. We saw how this operator allows us to find documents that don't match any of a specified set of conditions. By using the $nor operator in our queries, we can easily exclude documents that match certain criteria and narrow down our search results to only the documents that we need.