Re: About grammar and syntax on a possible relational language

On Mar 11, 4:42 pm, TroyK <cs_tr..._at_juno.com> wrote:
> On Mar 11, 4:55 am, Cimode <cim..._at_hotmail.com> wrote:
>
>
>
> > (snip)
> > SUMMARY
>
> > By running the following at definition time
>
> > [MAKE EMPLOYEE = {EMP# INT, LNAME CHAR, DOB DATE, SALARY INT}]
> > [MAKE RICH_EMPLOYEE = EMPLOYEE WITH SALARY > 100000]
> > [MAKE VIP_MEMBER = {RICH_EMPLOYEE}]
>
> > I am defining 3 relations differently and applying operators while
> > establishing a de facto foreign key between VIP_MEMBER and
> > RICH_EMPLOYEE as well as RICH_EMPLOYEE and EMPLOYEE. I use this de
> > facto references to be able to write
>
> > PRESENT2D [VIP_MEMBER WITH SALARY > 200000] --> 2 implicit JOINS.
>
> > What do you guys think. I initially thought about using SET instead
> > but I want to keep the idea of relation as a construct which is why I
> > use the verb MAKE. I am hoping the above example wil draw some
> > constructive comments..
>
> > Regards...
>
> Short comment/question on the syntax:
>
> PRESENT2D - does the name imply that there will be other n-dimensional
> presentations available (PRESENT3D, e.g.)?

Yes. Other examples of media functions are: OLAP
SENDFTP('192.168.10.20') --> built

the purpose of theses functions is to express the modalities and protocols by which the information is presented to users.

> Why not:
> [MAKE RICH_EMPLOYEE = {EMPLOYEE WITH SALARY > 100000}]
> (with curly braces around the derivation expression)? It seems a
> little "off" to use them only sometimes.
Because I reserved '[]' to relation operation and '{}' to relation definition. I will keep the remark in mind though

> Regarding derived relation definitions, what would the expected
> behavior be for VIP_MEMBER if the derivation for RICH_EMPLOYEE were to
> change after VIP_MEMBER was declared, e.g.:
> [MAKE RICH_EMPLOYEE = EMPLOYEE WITH SALARY > 150000]
>
> My assumption is that the VIP_MEMBER relation would "dynamically"
> derive from the new definition. Is this correct?
Yes. VIP_MEMBER is a derived relation from RICH_EMPLOYEE that is itself from EMPLOYEE..

Thanks for your comments...

> TroyK
Received on Tue Mar 11 2008 - 18:38:14 CET