Structured Query Language Questions

Ability to write and reason about queries using structured query language to extract and aggregate data from relational databases. Key capabilities include composing select statements with appropriate where clauses, grouping and aggregation, joining multiple tables with clear join keys, basic subqueries, and simple windowing or analytic patterns. Candidates should understand relational schema design, primary and foreign keys, basic performance considerations such as filtering and indexing, and how to translate business questions into reproducible queries for analysis and dashboards.