Comparison expressions ($eq, $gt in aggregation) in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the $eq operator do in MongoDB aggregation?

The $eq operator checks if two values are equal. It returns true if they are the same, otherwise false.

beginner

How does the $gt operator work in MongoDB aggregation?

The $gt operator checks if the first value is greater than the second value. It returns true if it is, otherwise false.

beginner

Write a simple MongoDB aggregation expression using $eq to check if the field status equals "active".

{ $eq: ["$status", "active"] }

beginner

In aggregation, what type of value do $eq and $gt return?

Both $eq and $gt return a boolean value: true or false.

intermediate

Why are comparison expressions like $eq and $gt useful in MongoDB aggregation?

They help filter or create conditions inside aggregation pipelines, allowing you to compare values and decide which documents to include or how to transform data.

What does { $eq: ["$age", 30] } check in an aggregation pipeline?

A If the field <code>age</code> is greater than 30

B If the field <code>age</code> is not equal to 30

C If the field <code>age</code> is less than 30

D If the field <code>age</code> equals 30

The $eq operator checks if the first value equals the second. Here it checks if age is exactly 30.

Which operator would you use to check if a value is greater than another in MongoDB aggregation?

A $gt

B $ne

C $lt

D $eq

$gt means 'greater than'. It returns true if the first value is bigger than the second.

What type of value do $eq and $gt return in aggregation?

A Number

B String

C Boolean

D Array

Both $eq and $gt return true or false, which are boolean values.

In the expression { $gt: ["$score", 50] }, what does it mean if the result is true?

A The score equals 50

B The score is greater than 50

C The score is less than 50

D The score is not a number

$gt returns true if the first value is greater than the second. Here, score is greater than 50.

Which of these is a valid use of $eq in an aggregation pipeline?

A { $eq: ["$price", 100] }

B { $eq: "$price", 100 }

C { $eq: "$price" }

D { $eq: [100] }

The correct syntax for $eq is an array with two values to compare, like ["$price", 100].

Explain how the $eq and $gt operators work in MongoDB aggregation and give a simple example of each.

Think about comparing values and returning true or false.

Describe a real-life situation where you might use $eq and $gt in a MongoDB aggregation pipeline.

Imagine sorting or filtering data like a list of users or products.