Examples of Aggregate Functions Find the numbers of tuples in the customer relation select count (* from customer remember stands for all attributes Same as. select count(customer-city) from customet Different from select count(distinct customer-city from customer Because customer-City is not a key COMP3311 Fall 2011 CSE, HKUST Slide 13COMP3311 Fall 2011 CSE, HKUST Slide 13 Examples of Aggregate Functions • Find the numbers of tuples in the customer relation. select count(*) from customer – remember * stands for all attributes – Same as: select count(customer-city) from customer – Different from: select count(distinct customer-city) from customer – Because customer-city is not a key