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

... 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...

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 ... (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...

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, ... 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...

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 ... 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...

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

... 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