Objective

Write a SQL query to calculate the number of monthly active users (MAUs) for February 2026.

Table Schema:

• user_actions

Task Requirements:

• An active user is someone who performed at least one action in both February 2026 and January 2026
• Any action type (sign-in, like, or comment) counts as activity
• A user performing multiple actions in the same month still counts as one active user
• Output the month in numerical format (2 for February)
  
  

Output columns: month, monthly_active_users

WITH jan_users AS (
    SELECT DISTINCT user_id
    FROM user_actions
    WHERE EXTRACT(MONTH FROM event_date) = 1
        AND EXTRACT(YEAR FROM event_date) = 2026
),
feb_users AS (
    SELECT DISTINCT user_id
    FROM user_actions
    WHERE EXTRACT(MONTH FROM event_date) = 2
        AND EXTRACT(YEAR FROM event_date) = 2026
)
SELECT
    2 AS month,
    COUNT(*) AS monthly_active_users
FROM feb_users f
JOIN jan_users j
    ON f.user_id = j.user_id;

Explanation

Step 1: Finding January Active Users

WITH jan_users AS (
    SELECT DISTINCT user_id
    FROM user_actions
    WHERE EXTRACT(MONTH FROM event_date) = 1
        AND EXTRACT(YEAR FROM event_date) = 2026
)

The first CTE collects all users who performed at least one action in January 2026. EXTRACT(MONTH FROM event_date) pulls the month number and EXTRACT(YEAR FROM event_date) pulls the year. DISTINCT ensures each user appears once regardless of how many actions they performed.

Step 2: Finding February Active Users

feb_users AS (
    SELECT DISTINCT user_id
    FROM user_actions
    WHERE EXTRACT(MONTH FROM event_date) = 2
        AND EXTRACT(YEAR FROM event_date) = 2026
)

The second CTE does the same for February 2026. This gives us the pool of users who were active in the current month.

Step 3: Finding Users Active in Both Months

FROM feb_users f
JOIN jan_users j
    ON f.user_id = j.user_id

An INNER JOIN on user_id keeps only users who appear in both CTEs. Users active in only January or only February are excluded. This is the core of the MAU definition: activity in both the current month and the previous month.

Step 4: Counting and Formatting the Output

SELECT
    2 AS month,
    COUNT(*) AS monthly_active_users

COUNT(*) counts the number of users in the joined result, giving the MAU for February 2026. The month is output as the integer 2 as required by the numerical format.