This mini project is designed for practicing and mastering SQL subqueries — from basic concepts like IN and NOT IN to more advanced patterns using aggregation and correlated subqueries.

Be sure that your results only list each employee once. In this lesson, you got to practice some more complex SQL queries, some of which required subqueries. There's still plenty more SQL to be had ...

Comorbidities can change the way your primary condition is managed or treated. For example, your healthcare provider may need to consider your comorbidities when prescribing medication, as some drugs ...