Databases Demystified a self teaching guide phần 1 doc

... Database Design Using Normalization 14 5 The Need for Normalization 14 7 Insert Anomaly 14 8 Delete Anomaly 14 8 Update Anomaly 14 8 Applying the Normalization Process 14 8 Choosing a Primary Key 15 1 First ... databases, including properties common to databases, prevalent database models, a brief his - tory of databases, and the rationale for focusing on the relational model....

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... several proprietary XML databases on the market. However, businesses have been reluctant to abandon relational data - bases and undergo a major paradigm shift in the way they organize and store data. So, ... considered a best practice because it can lead to a lack of data sharing. Moreover, placing geographic or organizational unit names in table names plays havoc every time the organ...

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... screen CHAPTER 12 Databases for Online Analytical Processing 3 01 Demystified / Databases Demystified / Oppel/ 225364-9 / Chapter 12 Data Marts A data mart is a subset of a data warehouse that supports ... contains more data than a data warehouse. e. The project has a lower overall cost than a data warehouse project. 16 . Building a data warehouse first, followed by...

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... relational databases were built by both IBM and UC Berkeley. e. Nearly all the commercial relational databases are descendents of either System R or INGRES. 18 . Currently available relational databases ... screen Constraints A constraint is a rule placed on a database object (typically a table or column) that restricts the allowable data values for that database object in some...

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... unmatched data to NULL, and because null values are not greater than 1/ 1 /19 98 (and in fact are not greater than, less than, or equal to anything), the criteria as written in Example 3-9 would eliminate ... row are called aggregate functions. The following table shows aggregate functions that are commonly used in relational databases: Function Name Description AVG Calculates the average...

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... that ends every SQL statement. In Oracle, a transaction is automatically started for each database user session as soon as the user connects to the database. At any time, the database user can ... table’s data. The ALTER TABLE Statement The ALTER TABLE statement may be used to change many aspects of the definition of a database table. Again, there is a wide variation in implementation a...

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... redundant data in tables • Storing summarized data in tables Note also that normalization is intended to remove anomalies from databases that are used for online transaction-processing systems. Databases ... Databases that store historical data used solely for analytical purposes are not as subject to insert, update, and de - lete anomalies. Chapter 12 contains more information on dat...

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... profile Composite Default screen 19 4 Databases Demystified Demystified / Databases Demystified / Oppel/ 225364-9 / Chapter 7 The Data Flow Diagram The data flow diagram (DFD) is the most data centric of all the ... other documents, such as narratives or decision tables. Relating Entities and Processes Once the database designer has completed logical database design and an ERD for th...

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... even to a different version of the same vendor’s database). Connecting Databases to Java Applications Java started as a proprietary programming language (originally named Oak) that was developed ... that binds the API to the particular database and platform, and a definition known as the ODBC data source contains the information necessary for a particular application to connect with...

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... 276 aggregate functions, 80–82, 83 with GROUP BY, 11 2 11 4 mixed aggregate and normal columns (error), 11 2, 11 3 simple, 11 2 ALTER TABLE statements, 11 9 12 1 analysis paralysis, 13 3 anomalies, 14 7 delete ... 62–63 D Data Control Language (DCL), 90, 12 2 12 4 Data Definition Language (DDL), 90, 11 8 12 2 data encryption, 256–257 data flow diagram, 19 4 19 6 data integrity, 214...

Ngày tải lên: 08/08/2014, 18:22