During June 2025, this developer focused on improving query correctness in the apache/calcite repository by addressing a core issue with NATURAL JOIN and JOIN USING operations under case-insensitive settings. They identified and fixed a bug where columns were incorrectly matched when case sensitivity was disabled, ensuring accurate join behavior across varying column name casing. The solution involved deep work with Calcite internals, leveraging Java and SQL expertise, and was validated through comprehensive regression tests. This contribution enhanced the reliability of cross-database workflows and demonstrated careful debugging, test-driven development, and a strong understanding of database query optimization principles.