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Practice data and prompts

SQL practice datasets with questions and answers

Work through 78 free SQL questions on 5 realistic relational datasets. Every set progresses from basic grouping and joins to reporting problems involving rates, time periods, window functions, and query grain. Open a prompt in the browser or download the full dataset and use your own SQL tools.

Each answer is real SQL checked against the same browser sample you query. Solutions are collapsed on the dataset guide, so you can attempt the question first and reveal the answer when you are ready. These are open-ended result questions rather than multiple-choice quizzes.

intermediate · 7 tables · 15 questions

Ecommerce Orders

Customers, products, orders, line items, payments, and returns at realistic online-retail volume.

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  1. Beginner

    How many orders are in the dataset, and how many distinct customers placed them?

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  2. Intermediate

    What is the gross revenue of each top-level category? Roll child categories up into their parent.

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  3. Advanced

    Compute total revenue two ways: the naive way, joining orders to order_items and payments in one query, and the correct way, aggregating each child table to one row per order first. Return both totals, the amount the naive query overstates, and by what percentage.

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advanced · 5 tables · 15 questions

Banking Transactions

Accounts, merchants, and two years of posted transactions with no stored balance to read off.

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  1. Beginner

    How many transactions are there in total, and how many distinct accounts do they cover?

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  2. Intermediate

    For the busiest account in the data, show each transaction with the running balance after it. Debits subtract, credits add.

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  3. Advanced

    Find the duplicate card payments: same account, same merchant, same amount, posted no more than 15 elapsed minutes after the one before it. Return both timestamps and the amount.

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advanced · 6 tables · 15 questions

SaaS Subscriptions

Organizations, plan intervals, invoices, and product usage for a B2B SaaS business.

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  1. Beginner

    How many organizations are there in each industry, biggest first?

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  2. Intermediate

    What was live monthly recurring revenue at the end of each month? A subscription counts for a month if it had started and had not yet ended.

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  3. Advanced

    Take each organization's first subscription month as its cohort. For each cohort, how many organizations were subscribed at the start of the month six months later?

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intermediate · 5 tables · 15 questions

Marketing Campaigns

Channels, campaigns, ad groups, and two years of daily performance where every metric is a ratio.

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  1. Beginner

    How many campaigns run on each channel, and how many are still running?

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  2. Intermediate

    Calculate the real click-through rate for each channel: total clicks divided by total impressions. Guard against channels with no impressions.

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  3. Advanced

    Compare first-touch and last-touch attribution. For each channel, how many conversions and how much revenue does each model give it?

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intermediate · 6 tables · 18 questions

Messy Student Records

Student, enrollment, and grade records merged from three schools, with the mixed formats, padding, and duplicates left to clean.

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  1. Beginner

    How many different ways is an enrollment's status written, and how many rows use each one?

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  2. Intermediate

    What are the ten most-enrolled courses once the course codes are cleaned to the catalog's form?

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  3. Advanced

    Parse enrolled_on into a real date using each school's own format. How many dates per school would land on the wrong day if you read them all as US dates?

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How to use the questions

  1. 1. Read the schema Identify the result grain, keys, and table relationships before writing the query.
  2. 2. Run your answer Open the prompt in SQLShed or download the files and work in your usual database client.
  3. 3. Compare solutions Reveal the tested answer, then compare result grain, filters, joins, grouping, and tie-breakers, not only the final rows.

Questions about the practice sets

Do these SQL dataset questions include answers?

Yes. Every question has a tested SQL solution on its dataset page. The solution stays collapsed until you choose to reveal it.

Can I run the SQL questions online?

Yes. Each question opens in SQLShed's browser playground with the correct dataset and a prompt in the editor. Nothing needs to be installed.

Can I download the practice datasets?

Yes. Each dataset guide links its available full downloads, including CSV, SQL, Parquet, or schema files depending on the dataset.