SQL Practice

Real-life business problems on real tables. Read the scenario, write the query, and get it checked instantly.

All topics SELECT & Filtering Sorting & Limits Aggregation Joins String & Date Functions Window Functions Subqueries NULL & CASE CTEs & Recursion Set Operators Analytics Patterns

All levels Basic Intermediate Expert

Best-selling product in each category

Window Functions

Solve challenge

Running total of revenue by month

Window Functions

Solve challenge

Employees paid above their department average

Subqueries

Solve challenge

The second order that beat the first

Window Functions

Solve challenge

Heartbeat shoppers: gaps between orders

Analytics Patterns

Solve challenge

Basket pairs: what sells together

Joins

Solve challenge

30-day retention by first-order cohort

Analytics Patterns

Solve challenge

Black Friday month: the 7-day rolling average

CTEs & Recursion

Solve challenge

The typical basket: median order value by country

Window Functions

Solve challenge

Seller scoreboard: three half-years side by side

Aggregation

Solve challenge

The net new MRR waterfall

Analytics Patterns

Solve challenge

Three swipes in ten minutes

Window Functions

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The deepest balance drawdown

Window Functions

Solve challenge

Does week-one API usage predict churn?

Analytics Patterns

Solve challenge

Most active card holder in every country

Window Functions

Solve challenge

Upgraded, regretted, downgraded

Joins

Solve challenge

The 30-day readmission rate per department

Window Functions

Solve challenge

Hot streaks: each club's longest run of wins

Analytics Patterns

Solve challenge

Span of control: who really runs the org?

CTEs & Recursion

Solve challenge

The second-highest salary in every country

Window Functions

Solve challenge

Quarter by quarter: how fast is Nordvik growing?

CTEs & Recursion

Solve challenge

Patients whose labs stayed abnormal on back-to-back tests

Analytics Patterns

Solve challenge

Gaps and islands: every driver's longest working streak

Window Functions

Solve challenge

Drivers whose rating slid three weeks in a row

Window Functions

Solve challenge

Hub detection with a self join

Joins

Solve challenge

Lahore to New York with at most two stops

CTEs & Recursion

Solve challenge

What does surge pricing really do?

Analytics Patterns

Solve challenge

Out and back within a week: round-trip travellers

Joins

Solve challenge

How much of the fleet really flies each month?

Analytics Patterns

Solve challenge

Sessionization: the ten longest listening sessions

Window Functions

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Longest listening streak (gaps and islands)

Analytics Patterns

Solve challenge

Month-1 and month-2 retention by sign-up cohort

Analytics Patterns

Solve challenge

Filling the empty days: May 2026 daily plays

CTEs & Recursion

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Listeners on a three-month growth run

Joins

Solve challenge

VIP outreach: the top 10 percent of listeners

Window Functions

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New versus returning listeners, month by month

CTEs & Recursion

Solve challenge