Databases Demystified a self teaching guide phần 3 potx

... 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 value for a ... printer profile Composite Default screen 78 Databases Demystified Demystified / Databases Demystified / Oppel/ 22 536 4-9 / Chapter 3 beauty of relational databases is that we need...

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... Quizzes and Final Exam 32 5 Chapter 1 32 5 Chapter 2 32 5 Chapter 3 326 Chapter 4 32 6 Chapter 5 32 6 Chapter 6 32 6 Chapter 7 32 6 Chapter 8 32 7 Chapter 9 32 7 Chapter 10 32 7 Chapter 11 32 7 Chapter 12 32 7 Index ... models, a brief his - tory of databases, and the rationale for focusing on the relational model. Properties of a Database A database is a collection of...

Ngày tải lên: 08/08/2014, 18:22

... Deleting database objects c. Adding new database objects d. Adding data items to existing database objects e. Deleting data items from existing database objects CHAPTER 1 Database Fundamentals 23 P:\010Comp\DeMYST \36 4-9\ch01.vp Monday, ... screen Constraints A constraint is a rule placed on a database object (typically a table or column) that restricts the allowable data values fo...

Ngày tải lên: 08/08/2014, 18:22

... 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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... profile Composite Default screen 194 Databases Demystified Demystified / Databases Demystified / Oppel/ 22 536 4-9 / Chapter 7 The Data Flow Diagram The data flow diagram (DFD) is the most data centric of all the ... profile Composite Default screen 200 Databases Demystified Demystified / Databases Demystified / Oppel/ 22 536 4-9 / Chapter 7 11. The basic components of a flo...

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... 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 organization changes. CHAPTER ... synchronizing data updates for any redundantly stored data • More expensive than the centralized model • Lack of guidelines and best practices for how to partition data and applicatio...

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... screen CHAPTER 12 Databases for Online Analytical Processing 30 1 Demystified / Databases Demystified / Oppel/ 22 536 4-9 / Chapter 12 Data Marts A data mart is a subset of a data warehouse that supports ... Default screen 30 2 Databases Demystified Demystified / Databases Demystified / Oppel/ 22 536 4-9 / Chapter 12 Here are some reasons for creating a data mart: •...

Ngày tải lên: 08/08/2014, 18:22