Tell about the most complex case you are proud of.

One of the most challenging cases I am proud of involved creating an interactive dashboard in Power BI for the sales department. It was necessary to consolidate data from multiple sources with different structures and ensure quick response times when filtering large volumes of data. I used DAX measures for dynamic calculations and optimized the data model to speed up loading. As a result, the dashboard helped management make decisions based on up-to-date analytics, which increased the department's efficiency.