What does index cardinality measure and why does it matter for query optimization? SQL Data AnalystMedium Try Now
In SQL window functions, what does ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING produce? SQL Data AnalystMedium Try Now
What problem does SCD Type 1 (Slowly Changing Dimension) create for analytics? SQL Data AnalystMedium Try Now
What does the following window expression do? AVG(salary) OVER (PARTITION BY dept ORDER BY hire_date ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) SQL Data AnalystMedium Try Now
What is the difference between TRUNCATE and DELETE when removing all rows? SQL Data AnalystMedium Try Now
What does the following subquery pattern do? SELECT * FROM employees WHERE salary > (SELECT AVG(salary) FROM employees) SQL Data AnalystMedium Try Now
What does the following calculate? SELECT month, revenue, revenue – LAG(revenue) OVER (ORDER BY month) AS mom_change FROM sales SQL Data AnalystMedium Try Now
What does the following query pattern detect? SELECT * FROM orders o WHERE NOT EXISTS (SELECT 1 FROM returns r WHERE r.order_id = o.order_id) SQL Data AnalystMedium Try Now
What does the GROUPING() function return when used with ROLLUP or CUBE? SQL Data AnalystMedium Try Now
In what scenario does an INNER JOIN produce the same result as a LEFT JOIN? SQL Data AnalystMedium Try Now
What does the NTILE(4) OVER (ORDER BY score DESC) assign to a row ranked 3rd out of 20? SQL Data AnalystMedium Try Now
