Draw the tree first: leaves at the bottom, the last operator at the top. Then write each level as a clause.
π name, title (σ year = 2026 (instructor ⋈ teaches ⋈ π course_id, title (course)))π name (σ dept_name = 'Comp. Sci.' (student) ⋈ σ semester = 'Winter' ∧ year = 2026 (takes))- How many tuples does
π dept_name (σ credits = 4 (course))return? - How many tuples does
π name, title (student ⋈ takes ⋈ course)return? List the common attributes of each natural join before you count.