Which of the following is NOT a relational operator in MongoDB?

In MongoDB, relational operators are used to compare values and determine the relationship between them, such as equality, greater than, and not equal. The operators $eq (equal), $gt (greater than), and $ne (not equal) are all part of this category, used primarily in query conditions to filter documents based on specified criteria.

On the other hand, the $add operator is not a relational operator but rather an arithmetic operator. It is used in aggregation pipelines to perform addition operations on numeric values. While it plays a crucial role in calculations and data manipulation, it does not serve the purpose of comparison between values.

Understand that knowing the distinctions between these types of operators is essential for querying and manipulating data effectively in MongoDB. This understanding helps developers choose the right operator for their use case, ensuring precise data retrieval and processing.