SQL Case study involving bank liabilities, loans, and balances - extensive JOINs and CASE statements

Bank case: JOIN liabilities, loans, balances on account/customer. Use CASE for categorization (asset vs liability), status logic. Structure: fact balances, dim products; join on keys. Example: SELECT a.account_id, CASE WHEN b.balance > 0 THEN 'Asset' ELSE 'Liability' END, SUM(l.amount) FROM accounts a JOIN balances b ON a.id = b.account_id JOIN loans l ON a.id = l.account_id GROUP BY 1,2. Use CTEs for clarity. Why it matters: Design choices compound at scale—wrong approach can cause 100× overhead. Scalability trade-offs: Profile before optimizing; validate on sample then full. Cost implications: Suboptimal choices multiply at billion-row scale.