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ch6-2 - Chapter 6 Integrity and Security Domain Constraints...

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1 ©Silberschatz, Korth and Sudarshan 6.1 Database System Concepts Chapter 6: Integrity and Security Chapter 6: Integrity and Security ! Domain Constraints ! Referential Integrity ! Assertions ! Triggers ! Security ! Authorization ! Authorization in SQL ©Silberschatz, Korth and Sudarshan 6.2 Database System Concepts Domain Constraints Domain Constraints ! Integrity constraints guard against accidental damage to the database, by ensuring that authorized changes to the database do not result in a loss of data consistency. ! Domain constraints are the most elementary form of integrity constraint. ! They test values inserted in the database, and test queries to ensure that the comparisons make sense. ! New domains can be created from existing data types " E.g. create domain Dollars numeric (12, 2) create domain Pounds numeric (12,2) ! We cannot assign or compare a value of type Dollars to a value of type Pounds. " However, we can convert type as below ( cast r . A as Pounds ) (Should also multiply by the dollar-to-pound conversion-rate)
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