Applied Mathematics for Database Professionals phần 6 pptx

... 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 by first defining a database ... result by specifying database predicates. These database predicates are called database constraints. • This formal model is your—the database professional’s—reference of th...

Ngày tải lên: 08/08/2014, 18:21

... constraints, and formally specifies these for the given example database design. Chapter 9 shows how you can precisely formulate queries in mathematics , and Chapter 10 shows ho w you can formally specify ... 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...

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... 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...

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... formal definition of a database state. We’ll often use a shorthand name for a given database state for convenience of reference in the text. Database Database is an informal term for the actual (business) ... a structured way (that is, conforming to the database design). Abstractly, a database is the cur- rent value of the database variable; it is the informal term for da...

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... 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 ... (see Figure 6- 8) that holds the yearly bonus for man- agers; it is also a specialization of EMP1. Figure 6- 8. Table MAN1 CHAPTER 6 ■ TUPLE, TABLE, AND DATABASE PREDICATES...

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... 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, ... tables. CHAPTER 6 ■ TUPLE, TABLE, AND DATABASE PREDICATES1 36 7451CH 06. qxd 5/14/07 10:37 AM Page 1 36 Exercises 1. Evaluate the truth value of the followi...

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... 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 ... be inserted into the database: tcrs1 := { (CODE;'AM4DP') , (DESC;&apos ;Applied Mathematics for Database Professionals& apos;) , (CAT;'DSG') , (DUR;5) } Fo...

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... transaction to commit successfully while the database state, CHAPTER 11 ■ IMPLEMENTING DATABASE DESIGNS IN ORACLE 266 7451CH11.qxd 5/15/07 2: 26 PM Page 266 • The delete TE view named v_[table_name]_dte: ... Here is the formal specification of this table constraint: CHAPTER 11 ■ IMPLEMENTING DATABASE DESIGNS IN ORACLE 268 7451CH11.qxd 5/15/07 2: 26 PM Page 268 Listing 11-25. Tuple...

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... ■ 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...

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... 244 concurrent, 266 , 284, 298 data integrity code execution models for , 265 –284 examples of, 2 26 2 36 formally specifying, 221–2 26 transition constraints data integrity code and, 2 46 implementing, 2 96 transition ... 221–233 database universe, 36, 77, 139, 3 06 defined, 92 queries and, 199–2 16 sample database design and, 167 –181 specification of, 325–330 specifying formall...

Ngày tải lên: 08/08/2014, 18:21