Data Modeling Essentials 2005 phần 9 ppsx
Data Modeling Essentials 2005 phần 9 ppsx
... Branch No Date 18 12/21 /93 Maintenance 1 12/25 /93 63 12/23 /93 Local Holiday 2 12/25 /93 3 12/25 /93 National Closure 4 12/25 /93 Date Reason 5 12/25 /93 12/25 /93 Christmas 6 12/25 /93 Figure 14.12 Post ... Date Reason 18 12/21 /93 Maintenance 1 12/25 /93 Christmas 63 12/23 /93 Local Holiday 2 12/25 /93 Christmas 3 12/25 /93 Christmas 4 12/25 /93 Christmas 5 12/25 /93 Christmas 6 12/...
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Data Modeling Essentials 2005 phần 1 ppsx
... Concepts 296 10 .9. 2 Separating Attribute Groups 297 10 .9. 3 Transferable One-to-One Relationships 298 10 .9. 4 Self-Referencing One-to-One Relationships 299 10 .9. 5 Support for Creativity 299 10.10 ... format. 4 ■ Chapter 1 What Is Data Modeling? Figure 1.1 An information system. Report Program DATABASE Program data Report Program data data ProgramProgram data data 1 Data...
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Data Modeling Essentials 2005 phần 3 ppsx
... presenting data models. 6 4.12 Benefits of Using Subtypes and Supertypes ■ 1 29 6 First described in Simsion, G.C., “A Structured Approach to Data Modelling,” Australian Computer Journal (August 198 9). Simsion-Witt_04 ... simple tables) to limit the power of our data modeling language. This is a nice idea in theory, but there are many facts about data that cannot be represented 4...
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Data Modeling Essentials 2005 phần 4 ppsx
... unit. 156 ■ Chapter 5 Attributes and Columns 5 Date, C.J. Relational Database Writings 198 9- 199 1, Pearson Education POD, 199 2, Ch. 12. Simsion-Witt_05 10/8/04 7:56 PM Page 156 key also meets basic ... currency datatype does not accommodate more than two digits after the decimal point, again the decimal datatype should be used. If the decimal datatype is not avail- able, the integer dataty...
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Data Modeling Essentials 2005 phần 2 potx
... HO Employee Number Qualification Description Qualification Year 01267 Bachelor of Arts 197 0 01267 Master of Arts 197 3 01267 Doctor of Philosophy 197 6 7 096 4 Bachelor of Arts 196 9 22617 Bachelor of Arts 197 2 22617 Master of Arts 197 7 Employee Table Qualification ... department data. Employee Number Qualification Description Qualification Year 01267 Bachelor of Arts 197 0 01267 Master...
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Data Modeling Essentials 2005 phần 5 pot
... Bulwer-Lytton 8.1 Data Modeling in the Real World In the preceding chapters, we have focused largely on learning the lan- guage of data modeling without giving much attention to the practicalities of modeling ... minimum list. 8.2.1 Recognition of Data Modeling Let us repeat what we said in Chapter 1: No database was ever built with- out a data model. Unfortunately, many datab...
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Data Modeling Essentials 2005 phần 6 pdf
... we use for selecting good 276 ■ Chapter 10 Conceptual Data Modeling Simsion-Witt_10 10/11/04 8: 49 PM Page 276 Chapter 10 Conceptual Data Modeling “Our job is to give the client not what he wants, ... they are 10 .9 One-to-One Relationships ■ 297 Figure 10. 19 Separate entity class for credit rating attributes. Client Credit Rating have apply to Simsion-Witt_10 10/11/04 8: 49 P...
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Data Modeling Essentials 2005 phần 7 potx
... accepting a data model. 10.16 Testing the Model with Sample Data If sample data is available, there are few better ways of communicating and verifying a data model than to work through where each data ... combina- tion of < ;Data Item 1 Name>, < ;Data Item 2 Name>, . . . and < ;Data Item n Name>.” 10.18 The Assertions Approach ■ 317 Simsion-Witt_10 10/11/04 8: 49...
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Data Modeling Essentials 2005 phần 8 pps
... Number State 2000 299 9 New South Wales 3000 399 9 Victoria 4000 499 9 Queensland 5000 599 9 South Australia etc. Figure 13.16 Data derivable across rows. Simsion-Witt_13 10/11/04 9: 54 PM Page 410 exist ... Malik 1234 2345 372 89 J Smith 1234 Assignment Date 27/2 /95 2/3 /95 28/2 /95 Figure 12.5 Alternative implementations of relationships in an SQL 99 DBMS. Simsion-Witt_12 10/11/04...
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Data Modeling Essentials 2005 phần 10 ppt
... some impact on data modeling. 16.2.1 Data Integration: Working with Existing Databases A data warehouse is not simply a collection of copies of records from source systems. It is a database that ... 16.6.2 shows an example.) The data modeler is required to fit the data into this 16.2 Characteristics of Data Warehouses and Data Marts ■ 4 79 Simsion-Witt_16 10/8/04 8:08 PM Pag...
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