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Sams Teach Yourself SQL in 24 Hours, Third Edition
By Ronald R. Plew, Ryan K. Stephens
Table of Contents
Hour  20.  Creating and Using Views and Synonyms


Views and synonyms, two important features in SQL, were discussed this hour. In many cases, these features are not used when they could aid in the overall functionality of relational database users. Views were defined as virtual tablesobjects that look and act like tables, but do not take physical space like tables. Views are actually defined by queries against tables and possible other views in the database. Views are typically used to restrict data that a user sees and to simplify and summarize data. Views can be created from views, but care must be taken not to embed views too deeply, to avoid losing control over their management. There are various options when creating views, and some are implementation-specific.

Synonyms, objects in the database that represent other objects, were also discussed. Synonyms are used to simplify the name of another object in the database, either by creating a synonym with a short name for an object with a long name or by creating a synonym on an object owned by another user to which you have access. There are two types of synonyms: PUBLIC and PRIVATE. A PUBLIC synonym is one that is accessible to all database users, whereas a PRIVATE synonym is accessible to a single user. A DBA typically creates a PUBLIC synonym, wheras each individual user normally creates his or her own PRIVATE synonyms.


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Sams Teach Yourself SQL in 24 Hours
Sams Teach Yourself SQL in 24 Hours (5th Edition) (Sams Teach Yourself -- Hours)
ISBN: 0672335417
EAN: 2147483647
Year: 2002
Pages: 275

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