Tables Used

orderdetails

Column	Type
orderdetailid	bigint
orderid	bigint
productid	bigint
quantity	bigint
unitprice	double precision
currencyid	bigint

orders

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

products

Column	Type
productid	bigint
name	text
description	text
category	text
price	double precision
supplierid	bigint
stockquantity	bigint

Expected Output

Column
productid
orderdate
quantity
unitprice
futureprice
pastprice

Two Orders Before, Two Orders After: The Price Prophecy :Analyze Product Price Changes Over Time with Past and Future Comparisons 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.

Analyze price changes across the timeline of trade.

Xorthax wants to analyze price trends for products over time. For each Product ID, find the Order Date, Quantity, current unit price and the unit price two orders before and after the current order date.

Write Your Query

Answer:

          select p.productid,
       o.orderdate,
       od.quantity,
       od.unitprice,
       lead(od.unitprice, 2) over (partition by p.productid
                                   order by o.orderdate) as futureprice,
                                  lag(od.unitprice, 2) over (partition by p.productid
                                                             order by o.orderdate) as pastprice
from orderdetails od
join products p on od.productid = p.productid
join orders o on od.orderid = o.orderid;

This simulates tracking price fluctuations for products across multiple orders, similar to monitoring retail or market trends.

You will practice working with sequential order data to compare values across different points in time.

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.

SQL for Data Analysis (O’Reilly)

SQL techniques tailored for analytics and reporting workflows.

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Tables Used

Expected Output

Two Orders Before, Two Orders After: The Price Prophecy :Analyze Product Price Changes Over Time with Past and Future Comparisons Intermediate

Analyze price changes across the timeline of trade.

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?

SQL for Data Analysis (O’Reilly)