Có 20+ tài liệu thuộc chủ đề "giáo trình sql cơ bản"
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Wiley Publishing, Inc., is not associated with any product or vendor mentioned in this book.. This book is dedicated to Jacqueline — my fondest pride and joy.. Other titles by this author include Oracle Data Warehouse Tuning for 10g (Burlington, MA: Digital Press, 2005), Oracle 9i: SQL Exam Cram 2 (1Z0-007) (Indianapolis: Que, 2004), Oracle SQL: Jumpstart with Examples (Burlington,...
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Part I: Approaching Relational Database Modeling — Part I examines the history of relational database modeling. It describes the practical needs the relational database model fulfilled. Chapter 1: Database Modeling Past and Present — This chapter introduces basic concepts behind database modeling, including the evolution of database modeling, different types of databases, and the very beginnings of how to go...
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Figure 1-9: The object database model.. Another benefit of the object database model is its inherent ability to manage and cater for extremely complex applications and database models. A discussion of the object database model in a book covering the relational database model is important because many modern applications are written using object methodology based SDKs such as Java. Object-Relational...
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These database model structures can be extremely large and complex and, therefore, very difficult to decipher.. In the worst case, analyze applications as well as the database model to confirm the operational functionality of the database and that it actually does what it should do. It could very well be the case that a new database model is required because...
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Figure 3-15 shows a data diagram with authors on the right of the diagram and their respective publica- tions on the left, in a one-to-many relationship. It is unlikely that a publisher who commissions and prints a book will also produce an audio tape version of the same title. The purpose of the EDITION table is to provide a way...
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This chapter examines the detail of the normalization process. The sequence of steps involved in the normalization process is called Normal Forms. The Normal Forms steps are the progressive steps in the normalization process.. In fact, the truth is that language use in the exact definitions for Normal Forms is so very precise and carefully worded that problems are caused....
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It is important to understand these 2NF relationships in the opposite direction such that BOOK entries depend on the existence of PUBLISHER and SUBJECT entries. On the contrary, the relationship between PUBLISHER and BOOK plus SUBJECT and BOOK are actually one-to-zero, one, or many. Figure 4-20 shows what the data looks like in the altered BOOK table with the new...
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Many-to-many. If tables are joined again using a three-table join, the resulting records will be the same as that present in the original table. It is a stated requirement of the valid- ity of 5NF that the post-transformation join must match records for a query on the pre-transformation table.. PRIMARY KEY (project,employee,manager). Note the composite primary key on all three...
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In the following expression, however, the conjunction of the second and third expressions is evaluated first. The precedence of evaluation of expressions in the next expression is changed by using the parentheses.. Breaking things into small things is what object- oriented design using programming languages such as Java are all about — breaking things into smaller constituent parts to make...
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Figure 6-1 shows reversal of the normalization processing applied in Figure 4-28, Figure 4-29, and Figure 4-30. Figure 6-2 shows reversal of normalization processing applied in Figure 4-31. Once again Figure 6-3 shows another application of the reversal of BCNF. This type of denormalization is shown in Figure 6-4.. A better solution might be a combination of collection arrays in...
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So, a data warehouse hogs machine resources. The Relational Database Model and Data Warehouses. The traditional OLTP (transactional) type of relational database model does not cater for data warehouse requirements. therefore, the needs of OLTP and data warehouse databases are completely contrary to each other, down to the lowest layer of hardware resource usage.. OLTP and data warehouse database differences...
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This chapter describes various factors affecting database performance tuning, as applied to different database model types. Database performance is the most important factor as far as any database or database model is concerned. If performance is not acceptable, your database model does not service the end-users in an acceptable manner. This chapter forms a bridge between database modeling and related...
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Chapter 11: Filling in the Details with a Detailed Design. Where would the human race be without planning? Probably still up in the trees hanging from gnarly branches, shouting “Aaark!” every now and again. Previous chapters in this book have examined not only the theory of how to create a relational database model but also some other interesting topics, such...
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The business rules of a company, when applied to a database model, become that database model. The business rules are the tables, relationships between those tables, and even the constraint rules (in addition to referential integrity constraints) in a database. In fact, the application of normalization to a set of initial company data tables is a more and more complex...
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There are other ways of building this data warehouse database model.. When planning any software project, including a database model design, there is often more than one person involved in a project. It is quite common in the software development field for project-tender budgets from multiple companies to be as much as 50 times different. It is often the case...
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In Figure 10-8, the relationship between the CATEGORY_PRIMARY and CATEGORY_SECONDARY tables is one-to-zero, one, or many. Figure 10-8: Parent records can exist and child records are not absolutely required (one-to-zero, one, or many).. This is especially true where facts stem from differing sources, such as BID in Figure 10-8. In Figure 10-8, a LISTING table record can be set as...
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4NF would change the OLTP database model in Figure 10-18 to that shown in Figure 10-20.. Figure 10-20: Applying 4NF to the OLTP database model.. seller_id seller popularity_rating join_date address return_policy international. buyer_id buyer popularity_rating join_date address Category_Primary. The sensibility of the application of 4NF, as shown in Figure 10-20, depends on applications. Once again, increasing the number of tables...
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Figure 10-37 shows the analyzed data warehouse database model, for online musician and band advertisements. Think about the records in the tables. Figure 10-38 takes another slant on this data warehouse database model by rolling all of these tables into a single fact table.. Figure 10-38 is a partially complete data warehouse database model, with all the facts rolled into...
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Figure 11-7: Defining field datatypes for the online auction house OLTP database model.. All that has been done in Figure 11-7 is that the field datatypes have been specified. Because of limita- tions of the version of the database modeling tool in use (and other software), note the following in Figure 11-7:. Datatypes are specifically catered for in the following...
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Business Rules and F ield Settings. This chapter covers the deepest layer of implementation into a database model — business rules.. Business rules are implemented into a database model by creating tables, establishing relationships between tables, identifying fields, their datatypes, and various other factors including things such as validation. There is also a brief section on applying business rules by...