This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Question 4- ( /8) Relations R and S have attributes a and b . Then, which of the properties below is (are) true for the following relational algebra queries: Q1: a ( R ) a ( S ) Q2: a ( R S ) (1) Q1 and Q2 produce the same answer. (2) The answer to Q1 is always contained in the answer to Q2. (3) The answer to Q2 is always contained in the answer to Q1. (4) There is no such relationship between answers of Q1 and Q2. Briefly explain your answer. Question 5-( /6) Assume the presence of a transaction table shown: Transaction Tno Vno Amount 1001 2 16.00 1002 2 19.00 1003 3 25.00 What does the following SQL queries return? select count(*), sum(amount) from transaction group by vno;...
View Full Document
This homework help was uploaded on 04/10/2008 for the course CSE 671 taught by Professor Hakanferhatosmanoglu during the Fall '06 term at Ohio State.
- Fall '06