Data Engineer • Coding • medium

Write a SQL query to find the second highest salary per department.

#Window Functions #SQL

Practice

Data Engineer • Coding • medium

Write a SQL query to compute a 7-day rolling average of daily sales.

#Window Functions #Analytics

Practice

Data Engineer • Coding • medium

Given a `user_logins` table with `user_id` and `login_date`, write a SQL query to calculate the 7-day rolling average of Daily Active Users (DAU) for the last 30 days.

#Window Functions #Rolling Averages #DAU

Practice

Data Engineer • Coding • easy

Given a `friend_requests` table (sender_id, receiver_id, date, status) and an `acceptances` table, write a SQL query to find the overall acceptance rate of friend requests by date.

#Joins #Aggregations #Ratios

Practice

Data Engineer • Coding • medium

Write a SQL query to find users who have interacted with a Meta ad and subsequently made a purchase on the advertiser's website within 24 hours. You have an `ad_clicks` table and a `conversions` table.

#Joins #Date/Time Functions #Attribution

Practice

Data Engineer • Coding • hard

Write a SQL query to calculate the retention rate of new users on a 1-day, 7-day, and 30-day basis. You are given a `user_activity` table with `user_id` and `activity_date`.

#Cohort Analysis #Retention #Self Joins #Conditional Aggregation

Practice

Data Engineer • Technical • medium

Explain the difference between OLAP and OLTP systems. When would you use each?

#OLAP #OLTP #Databases

Practice

Data Engineer • Technical • hard

How would you optimize a SQL query that is running slowly on a 1 billion row table?

#Query Optimization #Indexing

Practice

Data Engineer • Technical • medium

Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER().

#Window Functions #SQL

Practice

Data Engineer • Technical • medium

What is a materialized view? How does it differ from a regular view?

#Materialized Views #Performance

Practice

Data Engineer • Technical • medium

What are CTEs (Common Table Expressions) and how do they differ from subqueries?

#CTEs #SQL

Practice

Meta

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Interview Question Bank

Write a SQL query to find the second highest salary per department.

Write a SQL query to compute a 7-day rolling average of daily sales.

Given a `user_logins` table with `user_id` and `login_date`, write a SQL query to calculate the 7-day rolling average of Daily Active Users (DAU) for the last 30 days.

Given a `friend_requests` table (sender_id, receiver_id, date, status) and an `acceptances` table, write a SQL query to find the overall acceptance rate of friend requests by date.

Write a SQL query to find users who have interacted with a Meta ad and subsequently made a purchase on the advertiser's website within 24 hours. You have an `ad_clicks` table and a `conversions` table.

Write a SQL query to calculate the retention rate of new users on a 1-day, 7-day, and 30-day basis. You are given a `user_activity` table with `user_id` and `activity_date`.

Explain the difference between OLAP and OLTP systems. When would you use each?

How would you optimize a SQL query that is running slowly on a 1 billion row table?

Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER().

What is a materialized view? How does it differ from a regular view?

What are CTEs (Common Table Expressions) and how do they differ from subqueries?

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