SQL Interview Questions (Window Functions and CTE)

Write SQL to solve data analysis tasks (3 simple questions, easy–medium). You are expected to use CTEs and window functions (e.g., ROW_NUMBER()/RANK()/LAG()/LEAD()/SUM() OVER). Given table schemas and requirements in the interview, write runnable queries and explain your partition and order keys. Note: The original post did not include the exact prompts or schemas for the 3 SQL questions, so only the topic/type is summarized here.