What does a TRC query mean? More precisely, what is the set of answer tuples iven TRC query? The answer to a TRC query {T|p(T)}, as we noted earlier, is et of all tuples t for which the formula p(T) evaluates to true with variable T assi a tuple value + To complete this definition, we must state which signments of t

What does a TRC query mean? More precisely, what is the set of answer tuples iven TRC query? The answer to a TRC query {T|p(T)}, as we noted earlier, is et of all tuples t for which the formula p(T) evaluates to true with variable T assi a tuple value + To complete this definition, we must state which signments of t

Programming with Microsoft Visual Basic 2017

8th Edition

ISBN:9781337102124

Author:Diane Zak

Publisher:Diane Zak

Chapter12: Database Queries With Sql

Section: Chapter Questions

Problem 1MQ2

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What does an EXCEPT (MINUS) query care about operand order, while a UNION query doesn't?
Consider the following SQL Query: SELECT FNAME, DNAME FROM EMP AS E, DEPT AS D WHERE E.DNO = D.DNUMBER AND D.DNAME='CCI' AND SALARY > 15000; Draw the initial query tree for the above SQL query, and then show how the query tree is optimized by applying the Heuristic Rules. (You need to show the tree after applying a rule).
Question#1: Draw query tree for following relational queries. Also write SQL query for each relational query given. σsubject = "database"(Books) ∏ author (Books) ∪ ∏ author (Articles) σauthor = 'tutorialspoint'(Books Χ Articles) (πsName,p.pName,pa.Grade (σs.Age>25^pa.Grade=’A’ ((Student ⋈ Project_Allocation) ⋈ Project)))
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But why does the order of operands matter for UNION queries but not for EXCEPT (MINUS) searches?
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