SQL pattern · P01 · 13 problems

Filtering rows and conditions

Graded problems on combining conditions, matching patterns and filtering ranges, from easy to hard.

13 problems · about 1 h 20 min in all
Start with problem 01Filter to paid orders · 3 min
Learn it first · P01The filter that keeps unintended rowsAND groups before OR. Parentheses define the logic you meant.Read the lesson →

Easy

7 problems · about 30 min
01Filter to paid orders3 min →02Active premium customers4 min →03Products within a price band4 min →04Open high-priority tickets for one team5 min →05Newsletter sign-ups with a Gmail address5 min →06Trial sign-ups in March5 min →07Orders that weren't cancelled or refunded4 min →

Medium

4 problems · about 29 min
08Premium customers outside the US and Canada6 min →09Events in the last 24 hours7 min →10Parcels Eligible for the Standard Rate8 min →11Find the staging tables by their prefix8 min →

Hard

2 problems · about 23 min
12High-value fulfilled orders in a date window8 min →13Customers Eligible for a Marketing Campaign15 min →
Up next · P02

NULL changes how comparisons work

8 practice problems. Handle missing values correctly with IS NULL, COALESCE, and NULLIF.

Practise P02Read P02