SQL Practice

Customers from Lahore

SELECT & Filtering

Premium products above Rs 1,000

Sorting & Limits

How many orders were cancelled?

Aggregation

VIP outreach in emerging markets

SELECT & Filtering

Five fattest margins in Electronics

Sorting & Limits

Which sales channel loses the most orders?

Aggregation

How long does a parcel really take?

String & Date Functions

Signed up, never bought

Joins

Flagged card payments for the fraud desk

SELECT & Filtering

The five biggest paying plans right now

Sorting & Limits

How healthy is the loan book?

Aggregation

On time, late or still unpaid?

NULL & CASE

Payday money by month

String & Date Functions

Well-paid 2025 hires in Western Europe

SELECT & Filtering

The five biggest cheques in the transfer market

Sorting & Limits

Where does the payroll sit?

Aggregation

Length of stay month by month in 2025

String & Date Functions

Who is still in a bed?

NULL & CASE

Long-haul legs over 9,000 km

SELECT & Filtering

The five priciest tickets

Sorting & Limits

Zoomi city revenue scoreboard

Aggregation

Which weekday does the airline fly most?

String & Date Functions

How many completed trips never got a rating?

NULL & CASE

Premium fans in Brazil, Mexico and Turkey

SELECT & Filtering

The long play playlist

Sorting & Limits

Where do our listeners live?

Aggregation

Age groups and the people who never told us

NULL & CASE

Handle generator for the Q1 2026 sign-ups

String & Date Functions

Revenue by product category

Joins

Customers who never ordered

Joins

Delivered orders per month

String & Date Functions

Stars without words

NULL & CASE

Who pays how: payment method share

Subqueries

Podium finish: top 3 products per category

Window Functions

Which sellers get their goods sent back?

Joins

Repeat-purchase rate by country

CTEs & Recursion

Month-over-month revenue rollercoaster

Window Functions

Gadget and kitchen lovers who skip beauty

Set Operators

Paying customers who never opened the product

Joins

Where does the card money go?

Subqueries

Cloudpeak MRR, month by month

CTEs & Recursion

Rebuild the balance of account 15

Window Functions

Angry and behind on payments

Set Operators

Ageing report for overdue invoices

Analytics Patterns

Build the 2025-26 league table from raw results

Analytics Patterns

Earning more than your manager

Joins

Departments that keep patients longer than the hospital average

Subqueries

The top scorer of every club (ties included)

Window Functions

Promoted stars with a clean record

Set Operators

Which department sees the most abnormal lab results?

Joins

Busiest routes and what they cost in minutes

Joins

On-time scorecard by airline and quarter

NULL & CASE

Passengers who out-spend the average traveller

Subqueries

Building the airport watch list with set operators

Set Operators

The longest silence between two flights

Window Functions

Peak-hour demand ranking in every city

Window Functions

Rider cohorts by month of first trip

CTEs & Recursion

The silent shelf: tracks nobody has played

Joins

Which plan do customers walk away from?

Aggregation

Top 3 genres in every country

Window Functions

Superfans who never wander off

Subqueries

The comeback kids of 2026

Set Operators

Skip rate by device

NULL & CASE

The ten most valuable subscribers

NULL & CASE

Best-selling product in each category

Window Functions

Running total of revenue by month

Window Functions

Employees paid above their department average

Subqueries

The second order that beat the first

Window Functions

Heartbeat shoppers: gaps between orders

Analytics Patterns

Basket pairs: what sells together

Joins

30-day retention by first-order cohort

Analytics Patterns

Black Friday month: the 7-day rolling average

CTEs & Recursion

The typical basket: median order value by country

Window Functions

Seller scoreboard: three half-years side by side

Aggregation

The net new MRR waterfall

Analytics Patterns

Three swipes in ten minutes

Window Functions

The deepest balance drawdown

Window Functions

Does week-one API usage predict churn?

Analytics Patterns

Most active card holder in every country

Window Functions

Upgraded, regretted, downgraded

Joins

The 30-day readmission rate per department

Window Functions

Hot streaks: each club's longest run of wins

Analytics Patterns

Span of control: who really runs the org?

CTEs & Recursion

The second-highest salary in every country

Window Functions

Quarter by quarter: how fast is Nordvik growing?

CTEs & Recursion

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

Analytics Patterns

Gaps and islands: every driver's longest working streak

Window Functions

Drivers whose rating slid three weeks in a row

Window Functions

Hub detection with a self join

Joins

Lahore to New York with at most two stops

CTEs & Recursion

What does surge pricing really do?

Analytics Patterns

Out and back within a week: round-trip travellers

Joins

How much of the fleet really flies each month?

Analytics Patterns

Sessionization: the ten longest listening sessions

Window Functions

Longest listening streak (gaps and islands)

Analytics Patterns

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

Analytics Patterns

Filling the empty days: May 2026 daily plays

CTEs & Recursion

Listeners on a three-month growth run

Joins

VIP outreach: the top 10 percent of listeners

Window Functions

New versus returning listeners, month by month

CTEs & Recursion