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Course · Beginner to Expert
Answer real business questions from a database, from your first SELECT to a full board pack. Every exercise uses the data of Brightwell Supplies, a UK wholesaler.
4 of 4 tiers ready · about 32.5 hours of practice so far · Tier 1 free
Already use SQL at work? Take the free placement test and start at the right tier.
Answer a question from one table. · about 7.5 hours
0 of 71 exercises solved · 0 XP
Tables, rows and columns, and how to find your way around Brightwell's data.
0 of 7 solved
Pick the columns you need, give them clear names, and work out new values.
0 of 12 solved
Keep only the rows you need, using comparisons, AND/OR, IN, BETWEEN and LIKE.
0 of 16 solved
Find, exclude and fill in missing values, and avoid the classic = NULL mistake.
0 of 12 solved
Put rows in a useful order with ORDER BY, and keep only the top few with LIMIT.
0 of 10 solved
Count, total and average whole tables with COUNT, SUM, AVG, MIN, MAX and DISTINCT.
0 of 14 solved
10 questions · 30 minutes · pass to open Tier 2
Combine tables and summarise them. · about 9 hours
Tier 2 is part of Pro. Sign in, then pass the Tier 1 milestone exam to unlock it.
Totals, counts and averages for each channel, region or category, not just the whole table.
Keep only the groups that matter: the busy cities, the big customers, the best-selling products.
Put supplier names next to products, department names next to staff, and customers next to their orders.
Keep every row, even with no match, and find the customers who never ordered or the payments with no invoice.
Follow the links from customers to orders to order lines to products, and work out revenue.
Label rows (price bands, UK or overseas) and count with conditions, like IF in a spreadsheet.
Months and years, date ranges, month to date and year to date, and the days between two dates.
Tidy messy names and cities, join and cut text, and spot customers entered twice.
Answer analytical questions with subqueries, CTEs and window functions. · about 8 hours
Tier 3 is part of Pro. Sign in, then pass the Tier 2 milestone exam to unlock it.
Compare with an average, filter on a list from another table, and summarise a summary.
Break a long question into named steps that are easy to read and check.
Number rows with ROW_NUMBER, rank them with RANK and DENSE_RANK, and pick the top few in every group.
Month to date and year to date for every row, smoothed trends, and each item's share of the total.
Put last month next to this month, work out month-on-month growth, and measure the gaps between orders.
Stack results with UNION, compare lists with INTERSECT and EXCEPT, and find and remove duplicate records.
Group customers by when they started, build a retention table, and measure repeat purchase and churn.
Work like an analyst — change data, design tables and check data quality. · about 8 hours
Tier 4 is part of Pro. Sign in, then pass the Tier 3 milestone exam to unlock it.
Add, change and remove rows safely, and group changes into transactions.
Create tables with the right types, keys and rules, and split repeated data into tables of their own.
Give a query a name with CREATE VIEW, so every report uses the same business rules.
Read a query plan, avoid the habits that make queries slow, and add indexes where they help.
Find missing, invalid, duplicated and mismatched data, and build an audit you can run every day.
Turn rows into columns, find unbroken runs (gaps and islands), and measure a sales funnel.
Portfolio project · opens with Tier 3 · Pro
A sales analysis for the board: trends, categories, key customers, channels and accounts at risk.