What does EXPLAIN (or EXPLAIN ANALYZE in PostgreSQL) show about a query? SQL Data AnalystHard Try Now
Which SQL feature allows you to pivot rows into columns dynamically without hardcoding column names? SQL Data AnalystHard Try Now
What is the result of a CROSS JOIN between a table of 5 rows and a table of 8 rows? SQL Data AnalystHard Try Now
An analyst writes: SELECT dept, AVG(salary) FROM employees GROUP BY dept HAVING AVG(salary) > 70000. What does HAVING filter on here? SQL Data AnalystHard Try Now
Which isolation level prevents dirty reads but still allows non-repeatable reads? SQL Data AnalystMedium Try Now
You need the moving average of the last 3 rows including the current row. Which frame clause achieves this? SQL Data AnalystHard Try Now
A CTE is defined WITH cte AS (SELECT …). Which statement about CTEs is true? SQL Data AnalystHard Try Now
What does LAG(revenue, 2) OVER (ORDER BY month) return for the third row in a result set? SQL Data AnalystHard Try Now
Which window function calculates a running total of sales ordered by date within each region? SQL Data AnalystHard Try Now
What is the key behavioral difference between RANK() and DENSE_RANK() when there are tied values? SQL Data AnalystHard Try Now
A query uses ROW_NUMBER() OVER (PARTITION BY dept_id ORDER BY salary DESC). What does this produce? SQL Data AnalystHard Try Now
In what order does SQL evaluate the major clauses of a SELECT statement? SQL FundamentalsEasy Try Now
