HackerRank provides SQL challenges and assessment capabilities used for both practice and technical hiring. Practice problems free; Business assessment platform pricing varies. SQL challenges cover basics through advanced topics: SELECT, joins, aggregations, subqueries, and database-specific syntax. Problems organized by subdomain (Basic Select, Advanced Select, Aggregation, etc.) with difficulty ratings. The platform is widely used by companies for technical assessments—practicing on HackerRank familiarizes candidates with the assessment environment. Skills certification tests validate SQL proficiency with shareable certificates. Code submission environment supports MySQL, Oracle, MS SQL Server, and DB2 dialects. No AI features—automated testing against test cases. Employer platform enables custom assessment creation. Best suited for developers preparing for coding assessments and recruiters conducting technical screening. Page should cover: challenge categories, certification process, supported SQL dialects, employer assessment platform, comparison with LeetCode and CodeSignal, and assessment preparation tips.