Applied Mathematics for Database Professionals phần 8 doc

... count(*) from DEPT d where d.MGR = r.MGR); CHAPTER 11 ■ IMPLEMENTING DATABASE DESIGNS IN ORACLE 288 7451CH11.qxd 5/15/07 2:26 PM Page 288 where not exists(select 'This employee is assigned as a ... Here is the formal specification of this table constraint: CHAPTER 11 ■ IMPLEMENTING DATABASE DESIGNS IN ORACLE2 68 7451CH11.qxd 5/15/07 2:26 PM Page 2 68 Listing 11-25. Tuple Constr...

Ngày tải lên: 08/08/2014, 18:21

... shorthand name for a given database universe (just symbols) for conven- ience of reference in the text. Database State Database state is a formal term. It is a mathematical construct used to formally ... text. Database Database is an informal term for the actual (business) data that is stored in a computer in a structured way (that is, conforming to the database design). Abstr...

Ngày tải lên: 08/08/2014, 18:21

... you to a formal way of specifying a database via a database state. Formal Representation of a Database State Let’s consider a simple database design involving two table structures: one for employees ... The predicate class (tuple, table, or database) to which a business rule maps is fully dependent on the given database skeleton of the database design. For instance, predicate...

Ngày tải lên: 08/08/2014, 18:21

... 143, 185 , 190–196, 306 for mally specifying transactions and, 225 specifying for sample database design, 186 , 192–196 state transition predicates, 185 , 188 state transition universes, 185 , 190, ... functions, 77 database, 93 database design, 92 database management system (DBMS), 93 database state, 93 database universe, 92 database variable, 92 disjoint sets, 34 function...

Ngày tải lên: 08/08/2014, 18:21

... Ludwig Wittgenstein ( 188 9–1951) introduced truth tables as we know them today, based on the earlier work of Gottlob Frege ( 184 8–1925) and others during the 188 0s. After a formal notation was introduced, ... Page xxv Applied Mathematics for Database Professionals Copyright © 2007 by Lex de Haan and Toon Koppelaars All rights reserved. No part of this work may be reproduced or tr...

Ngày tải lên: 08/08/2014, 18:21

... and therefore a source of confusion. The section “Normal Forms” discusses normal forms in logic—not to be confused with normal forms of data (defined for database design purposes). Normal forms ... following two normal forms for predicates: • Conjunctive normal form is a predicate rewritten in the format of an iterated AND. • Disjunctive normal form is a predicate rewritten in the forma...

Ngày tải lên: 08/08/2014, 18:21

... limit regarding database professionals, then there cannot be a result with an average score of A for database professionals (r egardless of the course), and if ther e is a limit regarding non -database professionals, ... SPECIFYING DATABASE DESIGNS1 48 7451CH07.qxd 5/15/07 9:43 AM Page 1 48 • Database constraints: These are database predicates that you specify inside the d...

Ngày tải lên: 08/08/2014, 18:21

... constraints for our example database design. This definition specifies them by name only. In Listing 8- 8, you’ll find the formal specification for each of these named constraints. ■Note In Listing 8- 7 ... set of database states called the database universe. It holds the admissible database states for the database being specified. You can con- struct a database universe b...

Ngày tải lên: 08/08/2014, 18:21

... of a database; they enable you to extract infor- mation from a database that is relevant for you. • You can formally represent a query as a function over a database universe. For every database ... database: tcrs1 := { (CODE;'AM4DP') , (DESC;&apos ;Applied Mathematics for Database Professionals& apos;) , (CAT;'DSG') , (DUR;5) } For your convenience,...

Ngày tải lên: 08/08/2014, 18:21

... ■ FORMAL DEFINITION OF EXAMPLE DATABASE3 14 7451AppA.qxd 5/15/07 9:45 AM Page 314 Formal Definition of Example Database In this appendix, we deliver the formal specification of the example database ... salary. We hold additional information for all sales representatives in a separate table ( SREP). We hold additional information for employees who no longer work for the company (tha...

Ngày tải lên: 08/08/2014, 18:21