PPT Slide

Typed View Hierarchies

• Now create typed views (and subviews)

create view vperson of VPerson_t (ref is oid user generated) as

select VPerson_t(Varchar(oid)), name from only (person);

create view vemp of VEmp_t under vperson

(dept with options scope vdept) as

select VEmp_t(Varchar(oid)), name, VDept_t(Varchar(dept))

from emp where salary > 0;

create view vstudent of VStudent_t under vperson as

select VStudent_t(Varchar(oid)), name,

case when major like '%Engineer%' then 'Geek'

else 'non-Geek' end

from student;

create view vdept of VDept_t ...;

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