Project Operation-selection of columns (Attributes) Relation r. AB C X 10 1 X 20 1 1 B 40 2 ΠAc(r) AC AC X 1 C 1 1 二 2 2 Database System Concepts-6th Edition 2.10 @Silberschatz,Korth and SudarshanDatabase System Concepts - 6 2.10 ©Silberschatz, Korth and Sudarshan th Edition Project Operation – selection of columns (Attributes) Relation r: A,C (r)