Re: Normalization and DBMS

Dawn M. Wolthuis wrote:
> If you use Date's terminology, you need GROUP and UNGROUP operators
> in your language. This could also be NEST and UNNEST. The language
> used with PICK, for example, reads easier than SQL and includes such
> language as "WITH EVERY" so you get
>
> LIST STUDENTS WITH EVERY MAJOR <> "MATH"
>
> Did that answer the question? --dawn

Suppose there is some extra information about each "Major", maybe the name of the person in charge of it or something.

In the relational model there would be a separate relation to hold the majors, so we'd just have extra columns there.

We'd have a "students" relation with a many-to-many relationship to a "majors" relation, and a "student-major" relation to resolve this many-to-many relationship.

How would this be done in Pick?

Are the entries in multi-valued fields always the full text, or are they ever id numbers that correspond to a different file? e.g suppose you had 1=MATH, 2=ENGLISH, 3=PHYSICS. Would you just store the numbers 1,2,3 in the multivalued "major" column and have a separate file for the lookups? How would the query be written then in Pick?

Paul. Received on Tue May 11 2004 - 23:40:59 CEST