Introduction to Recursion

Recursion is a phenomenon where something is defined in terms of itself. In computer science, recursion refers to a function that calls itself as part of its definition. In the sense of divide and conquer, recursion poses the opportunity to solve a complex problem in smaller, simple steps. So far, our understanding of SQL without recursion implies that a query terminates since SQL cannot loop forever. At the same time, we know that any SQL query can be evaluated efficiently in$\mathcal{O}(r^c)$ ...