Write optimized and secure database queries using parameterized queries, eager loading, and proper indexing strategies. Use this skill when writing database queries, constructing SQL statements, using ORM query methods, implementing data fetching logic, preventing SQL injection attacks, optimizing query performance, avoiding N+1 query problems, selecting specific columns instead of all data, implementing transactions for related operations, setting query timeouts, caching expensive queries, or working with WHERE clauses, JOINs, and ORDER BY statements. Apply this skill when fetching data from databases, optimizing slow queries, refactoring data access code, or reviewing query security and performance.