Date expressions ($year, $month, $dayOfMonth) in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the $year date expression do in MongoDB?

The $year expression extracts the year part from a date value in MongoDB documents.

beginner

How does $month work in MongoDB date expressions?

The $month expression extracts the month (1-12) from a date value in MongoDB documents.

beginner

What value range does $dayOfMonth return in MongoDB?

$dayOfMonth returns the day of the month as a number from 1 to 31, based on the date value.

intermediate

Write a MongoDB aggregation snippet to get the year from a field called createdAt.

Use { $year: "$createdAt" } inside a $project or $addFields stage to extract the year.

intermediate

Why are date expressions like $year, $month, and $dayOfMonth useful in MongoDB?

They help break down dates into parts for filtering, grouping, or formatting data easily in aggregation pipelines.

What does { $month: "$dateField" } return in MongoDB?

A The month number (1-12) from the dateField

B The day of the week from the dateField

C The year from the dateField

D The full date as a string

$month extracts the month number (1 to 12) from a date value.

Which expression extracts the day of the month from a date in MongoDB?

A <code>$dayOfMonth</code>

B <code>$dateToString</code>

C <code>$dayOfYear</code>

D <code>$dayOfWeek</code>

$dayOfMonth returns the day number (1-31) of the month from a date.

If a date is '2024-06-15', what will { $year: "$date" } return?

A 6

B 2024

C 15

D June

$year extracts the year part, so it returns 2024.

Which MongoDB stage commonly uses $year, $month, and $dayOfMonth?

A <code>$match</code>

B <code>$group</code>

C <code>$project</code>

D All of the above

These expressions can be used in $match, $group, and $project stages for filtering, grouping, or reshaping data.

What is the valid range of values returned by $month in MongoDB?

A 0 to 11

B 1 to 31

C 1 to 12

D 0 to 23

$month returns months numbered 1 through 12.

Explain how to extract the year, month, and day from a date field in MongoDB aggregation.

Think about breaking down a date into parts using MongoDB expressions.

Describe a real-life scenario where extracting year, month, and day from dates in MongoDB would be helpful.

Consider how businesses analyze data over time.