Mid-Level SQL Test

This test targets mid-level SQL practitioners and emphasizes relational thinking and moderate query complexity. It requires confident use of JOINs, GROUP BY, subqueries (including correlated subqueries), and conditional logic. The schema and data are realistic and stable (APPXS_employee, APPXS_department, APPXS_educationlevel), allowing for deterministic output and automated evaluation. This version includes 7 coding questions and 3 theoretical questions.