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Views. View Modifications Using Triggers. View Modifications: Triggers. Modifying views Once V defined, want to modify V like any table Modifications to V rewritten to modify base tables Unlike queries, cannot be automated in general. View Modifications: Triggers.

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  1. Views View Modifications Using Triggers

  2. View Modifications: Triggers Modifying views • Once V defined, want to modify V like any table • Modifications to V rewritten to modify base tables • Unlike queries, cannot be automated in general

  3. View Modifications: Triggers Modifications to V rewritten to modify base tables (1) Rewriting process specified explicitly by view creator +Can handle all modifications – No guarantee of correctness (or meaningful) (2) Restrict views + modifications so that translation to base table modifications is meaningful and unambiguous + No user intervention – Restrictions are significant

  4. View Modifications: Triggers Modifications to V rewritten to modify base tables (1) Rewriting process specified explicitly by view creator Using special INSTEADOF triggers Demo: simple college admissions database College(cName,state,enrollment) Student(sID,sName,GPA,sizeHS) Apply(sID,cName,major,decision)

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