# Tutorial2 - Tutorial 2 Problem 1: Relational Algebra...

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Tutorial 2 Problem 1: Relational Algebra Consider the following relations: Server(realm_id, realmName, physical_location, ip_address) Account(account_id, username, password_enc) Characters(char_id, character_name, character_class, level, account_id, realm_id) Each character can belong only to 1 account and 1 server. Each account can have many characters, on many servers. Give the queries in relational algebra to answer the following questions. You should use only the basic operators plus join (set union, set difference, selection, projection, renaming, and join). You should use proper notation (e.g. σ for a selection operator, π for a projection operator, x for a Cartesian product, ρ for a renaming operator, and | ><| for a join operator.) 1. Find the char_id of all characters that belong to the account with username "Beowulf" 2. Find the account_id of accounts that only have a character on the "Thor" realmName. 3. Find the character_name of all characters that are of character_class "Warrior"

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## This note was uploaded on 02/17/2012 for the course CS 411 taught by Professor Winslett during the Fall '07 term at University of Illinois at Urbana–Champaign.

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Tutorial2 - Tutorial 2 Problem 1: Relational Algebra...

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