An ACS (Access Control System) Query Developer designs, develops, and optimizes database queries. They are responsible for creating scripts to retrieve, analyze, and manipulate data from ACS systems, integral for security and access control. Their work involves understanding business requirements, creating complex SQL queries, and ensuring data integrity and security. They also troubleshoot and optimize database queries for performance and efficiency. Their role may also involve creating detailed reports based on the data retrieved and presenting their findings to management. They must have a good understanding of database structures, principles, theories, and practices.