// querylab
Practice SQL the way the interview asks it.
Real PostgreSQL, real quick-commerce datasets, right in your browser. Write a query, run it, check it against the edge cases.
// medium
paid
Order status labeling with NULL and casing traps
sql fundamentalssolve →
// medium
paid
Conditional aggregation and a display label
sql fundamentalssolve →
// medium
paid
Product code cleanup with SUBSTRING, REPLACE, and LPAD
sql fundamentalssolve →
// medium
paid
Delivery window and day-of-week analysis
sql fundamentalssolve →
// medium
paid
Monthly revenue report with price tiers
sql fundamentalssolve →
// medium
paid
Unix timestamp signups: days-since conversion
sql fundamentalssolve →
// medium
paid
Formatting and parsing a booby-trapped date string
sql fundamentalssolve →
// medium
paid
Nested CASE, conditional aggregation, and HAVING
sql fundamentalssolve →
// medium
paid
Month-end clamping and leap-year renewal edge cases
sql fundamentalssolve →
// medium
paid
Loyalty tier custom sort and zero-padded customer codes
sql fundamentalssolve →