Business case questions

A business case question sounds like a stakeholder, not like a SQL exercise: “Where are our customers spending?”, “Which accounts should the dormancy team look at?”, “Why are customers leaving?”. There is no single right query until you have decided what exactly to measure. Interviewers grade that decision as much as the SQL.

Use four moves:

1. Define the decision. What will someone do with the answer? (Target a campaign, contact dormant customers, fix a product gap.) This tells you the grain and the time window.
2. Define the metric in one sentence, including what is excluded: “2025 card and online spending, excluding purchases that were later reversed, grouped by category.”
3. Hunt the business traps in the data: rows that look like activity but are not (reversals, internal transfers, failed payments, test accounts, trials), names that are spelled several ways, flags that lag behaviour.
4. Answer in a sentence with the number, then the caveat: “Home and bills dominates 2025 spending; rent and school fees drive it. Five percent of card spend has no category and is excluded.”

The first four exercises use Rawabi Bank (bank). Every transaction amount is positive and direction says whether money came in or went out; reversed purchases appear as a separate credit row pointing to the original; merchants arrive from the card network with inconsistent spelling; joint accounts have several holders in account_holders. The last two use Mizan Cloud (saas) subscriptions.