SQL practice

26 questions

• Big delivered orders

  Filtering and sorting · E-commerce · Online shop

  Easy

• Orders by status

  Aggregation · E-commerce · Online shop

  Easy

• Repeat buyers

  GROUP BY and HAVING · E-commerce · Online shop

  Easy

• Spend per customer

  Joins · E-commerce · Online shop

  Medium

• Customers who never ordered

  NULLs and anti-joins · E-commerce · Online shop

  Medium

• Employee and manager

  Self joins · HR analytics · Company directory

  Medium

• Top earner per department

  Window functions · HR analytics · Company directory

  Medium

• Visit → signup → purchase funnel

  CTEs and funnels · SaaS / product · Product usage and revenue

  Medium

• Running total per customer

  Window functions · E-commerce · Online shop

  Hard

• Month-over-month growth

  LAG and growth rates · SaaS / product · Product usage and revenue

  Hard

• Premium members by city

  Joins and aggregation · Food delivery · ClearBite food delivery

  Easy

• Big orders in the Diwali rush

  Filtering dates and sorting · Food delivery · ClearBite food delivery

  Easy

• Menu prices by category

  Aggregation · Food delivery · ClearBite food delivery

  Easy

• Coupon performance, including unused coupons

  LEFT JOIN and COALESCE · Food delivery · ClearBite food delivery

  Medium

• Cancellation rate by payment method

  Conditional aggregation · Food delivery · ClearBite food delivery

  Medium

• Average order value by city

  Joins and aggregation · Food delivery · ClearBite food delivery

  Medium

• Peak ordering hours

  Dates and LIMIT · Food delivery · ClearBite food delivery

  Medium

• Restaurants with no December orders

  Anti-joins · Food delivery · ClearBite food delivery

  Medium

• On-time delivery rate by city

  Timestamps and intervals · Food delivery · ClearBite food delivery

  Medium

• Delivery time by month

  Timestamps and intervals · Food delivery · ClearBite food delivery

  Medium

• Repeat rate by acquisition channel

  CTEs and NULLs · Food delivery · ClearBite food delivery

  Medium

• Do late deliveries get worse ratings?

  CASE and NULLs · Food delivery · ClearBite food delivery

  Medium

• Best-selling dish in each cuisine

  Window functions · Food delivery · ClearBite food delivery

  Hard

• First-month retention by signup cohort

  Cohorts · Food delivery · ClearBite food delivery

  Hard

• Top 3 restaurants in each city

  Window functions · Food delivery · ClearBite food delivery

  Hard

• Did WELCOME50 bring customers back?

  Window functions and EXISTS · Food delivery · ClearBite food delivery

  Hard

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