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C20.0046: Database Management Systems Lecture #1 - page 22 / 40

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M.P. Johnson, DBMS, Stern/NYU, Sp2004

22

Example: university database

Conceptual schema:

Students(ssn: string, name: string, login: string, age: int, gpa: real)

Courses(cid: string, cname: string, credits: int)

Enrolled(sid:string, cid:string, grade: string)

Physical schema:

Relations stored as unordered text files.

Indices on first column of each rel

External Schema (View):

Course_info(ssn: string, name: string)

My_courses(cname: string, grade: string)

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