SQL interview questions

10 questions with answers, grouped by topic.

Combining data

Every join type, multi-table joins, and set operations.

3

Why might a LEFT JOIN behave like an INNER JOIN?intermediate How do you find rows in one table with no match in another?beginner What is the difference between UNION and UNION ALL?beginner

Window functions

OVER, partitioning, ranking, LAG/LEAD and running totals.

2

Explain the difference between RANK, DENSE_RANK and ROW_NUMBER.intermediate How would you calculate month-over-month growth?intermediate