SQL Data Cycle Review
SQL data cycle review for quant interviews, covering joins, windows, aggregation, time-series data, debugging, data quality, and final drills.
Candidates consolidating SQL and data-query interview prep.
Review SQL fundamentals
Core SQL prep should cover SELECT, WHERE, GROUP BY, HAVING, joins, subqueries, CTEs, CASE, date logic, and window functions.
Review data correctness
For quant data, correctness depends on grain, keys, duplicates, nulls, timestamps, row counts, and whether joined information was available at decision time.
Review market and experiment examples
Practice market data, trade data, simple PnL, and A/B testing queries. These force joins, time logic, aggregation, and validation checks.
Concrete final drill
Write one query with a join, one with a window function, one with conditional aggregation, and one debugging checklist for a wrong row count.
Common mistakes
Candidates often stop when the query runs. The interview answer is stronger when it includes checks proving the query answers the intended question.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.