Tables Used

orders

Column	Type
orderid	bigint
customerid	bigint
orderdate	timestamp without time zone
totalamount	double precision
status	text

Expected Output

Column
customerid
largestorder
rank1
rank2

Order Titans of the Stars :Rank Customers by Their Largest Single Order Value with Tie-Aware Results Intermediate

Q: Do I need advanced SQL to attempt this?

This problem is labeled as Intermediate. It assumes you’ve written a few window function queries before, but you don’t need to be an expert. Use the hints and explanations if you get stuck — they’re there to help you think through the logic.

Spot the customers with the most orders and compare their rankings.

Xorthax wants to understand how frequently each customer shops at his trading post. Calculate how many orders each customer has placed, then assign two types of rankings: one that gives tied customers the same position without skipping any numbers, and another that assigns the same position to ties but does skip numbers

Write Your Query

Answer:

          with customerlargestorder as
  (select customerid,
          count(orderid) as ordercount
   from orders
   group by customerid)
select customerid,
       ordercount,
       dense_rank() over (
                          order by ordercount desc) as rank1,
                         rank() over (
                                      order by ordercount desc) as rank2
from customerlargestorder;

It reflects sales performance analysis where businesses identify customers responsible for the highest-value individual purchases.

You’ll practice ranking aggregated values while ensuring tied results are treated consistently and fairly.

This problem is labeled as Intermediate. It assumes you’ve written a few window function queries before, but you don’t need to be an expert. Use the hints and explanations if you get stuck — they’re there to help you think through the logic.

Yes. Every problem comes with optional hints you can reveal one at a time, plus a fully worked step-by-step solution. You decide how much help you want while practicing.

All problems on PracticeWindowFunctions.com are completely free and can be solved without creating an account. Right now there are over 80 practice problems, with new ones added regularly.

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Tables Used

Expected Output

Order Titans of the Stars :Rank Customers by Their Largest Single Order Value with Tie-Aware Results Intermediate

Spot the customers with the most orders and compare their rankings.

What real-world scenario does this represent?

What SQL concepts will I practice here?

Do I need advanced SQL to attempt this?

Will I get hints and step-by-step explanations if I get stuck?

Are the problems free to access, and how many are available?

Ace the Data Science Interview