Applied Mathematics for Database Professionals phần 9 pdf

... Report RJ 599 , 196 9. Codd, E. F. The Relational Model For Database Management,Version 2. Reading, MA: Addison- Wesley, 199 0. Recommended Reading on Relational Database Management Date, C. J. Database ... ■ 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...

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... 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...

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... (partno; [1 99 9]) ,(name; varchar(12)) ,(instock; [0 99 ]) ,(price; [1 500]) } CHAPTER 5 ■ TABLES AND DATABASE STATES 97 7451CH05.qxd 5/4/07 3:57 PM Page 97 Given table T11 and T6, you can formally ... chr_EMP chr_EMP := { (empno; [100 99 9]) ,(ename; varchar(20)) ,(job; {'MANAGER','CLERK','TRAINER'} ) ,(sal; [2000 90 00]) ,(deptno; [10 99 ]) } For...

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... expression denotes set [1000 99 99] . The definition of characterization chr_EMP tells us the following: • EMPNO values are positive integers within the range 1000 to 99 99. • ENAME v alues ar e v ar iable ... 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...

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... 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...

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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 ... database: tcrs1 := { (CODE;'AM4DP') , (DESC;&apos ;Applied Mathematics for Database Professionals& apos;) , (CAT;'DSG') , (DUR;5) } For your convenience,...

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... Attribute Constraints for SREP Table Structure alter table SREP add constraint srp_chk_empno check (empno > 99 9); alter table SREP add constraint srp_chk_targ check (target > 99 99) ; alter table ... Attribute Constraints for MEMP Table Structure alter table MEMP add constraint mmp_chk_empno check (empno > 99 9); alter table MEMP add constraint mmp_chk_mgr check (mgr >...

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... 143 defined, 93 queries and, 199 –201 specifying formally, 98 top-down view of, 141 transactions and, 221–233 database universe, 36, 77, 1 39, 306 defined, 92 queries and, 199 –216 sample database design and, ... 1 09 average operator (AVG), 112 binary relations, 69 cardinality of sets, 29 Cartesian product, 39 compatible functions, 77 database, 93 database design, 92 data...

Ngày tải lên: 08/08/2014, 18:21