What does LATERAL (or CROSS APPLY in SQL Server) allow in a FROM clause? SQL Data AnalystHard Try Now
Which SQL construct allows you to define a temporary named result that can reference itself for hierarchical queries? SQL Data AnalystHard Try Now
What is the purpose of statistics in SQL Server or PostgreSQL query optimization? SQL Data AnalystHard Try Now
You observe that a query performs well with a small dataset but degrades quadratically as data grows. Which join type is the likely culprit? SQL Data AnalystHard Try Now
What SQL technique efficiently calculates subtotals and grand totals in a single query? SQL Data AnalystHard Try Now
Which type of SQL join can be used to detect rows in one table that have no corresponding rows in another? SQL Data AnalystHard Try Now
What does FIRST_VALUE(revenue) OVER (PARTITION BY region ORDER BY sale_date) return for each row? SQL Data AnalystHard Try Now
In window functions, what is the difference between RANGE and ROWS frame modes? SQL Data AnalystHard Try Now
What is index cardinality and why does it matter for query optimization? SQL Data AnalystHard Try Now
Which execution plan operator typically indicates that an index is not being used and a full scan is occurring? SQL Data AnalystHard Try Now
What does ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING as a window frame produce? SQL Data AnalystHard Try Now
What does the EXISTS operator do differently from IN when used in a subquery? SQL Data AnalystHard Try Now
You need to find the second-highest salary in a table without using TOP/LIMIT. Which approach works in standard SQL? SQL Data AnalystHard Try Now
