Re: How do you implement this?

#1

"Diego Berge" <dberge (AT) privacy (DOT) net> wrote

Quote:

Given a series of events E1, E2, ... En occurring in time (so E1 occurs
from
E1(t0) to E1(t1), E2 from E2(t0) to E2(t1) and so on)

Given a series of arbitrary conditions (C) happening at one point (t) in
time, where the conditions are the simultaneous occurrence of a set of (or
combinations of sets of) events E at time t

Examples:

C1 = E1 & E2 & E3;
C2 = (E1 & E2) | E3;
C3 = (E1 & E2) | (E3 & E4);

I'd suggest that time model consistent concatenating events like C1 is much
more simple than the one that can accomodate disjunctions like C2 and C3.

Quote:

C1(t) would be true if and only if:
(E1(t0) <= C1(t) <= E1(t1)) &
(E2(t0) <= C1(t) <= E2(t1)) &
(E3(t0) <= C1(t) <= E3(t1))

C2(t) would be true if and only if:
((E1(t0) <= C2(t) <= E1(t1)) &
(E2(t0) <= C2(t) <= E2(t1))) |
(E3(t0) <= C2(t) <= E3(t1))

That sounds like constraint database.

Quote:

My question:

How do you implement this in the context of a relational database? Or you
simply don't? I've been scratching my head for a couple hours now, this
doesn't seem to be my day for it.

For those who wonder what this is about, I'm working on a personnel
training
database. In plain English, the above means: if you have done this and
this and this course, or that one, you are qualified, on this date, to do
job X.

Why time is important at all in this context? If you have done this and
this and this course, or that one, you are qualified disregarding the time.

#2

Mikito Harakiri wrote:

Quote:

"Diego Berge" <dberge (AT) privacy (DOT) net> wrote in message
news:bkuv6m$68c7e$1 (AT) ID-186969 (DOT) news.uni-berlin.de...

Given a series of events E1, E2, ... En occurring in time (so E1 occurs

from

E1(t0) to E1(t1), E2 from E2(t0) to E2(t1) and so on)

Given a series of arbitrary conditions (C) happening at one point (t) in
time, where the conditions are the simultaneous occurrence of a set of (or
combinations of sets of) events E at time t

Examples:

C1 = E1 & E2 & E3;
C2 = (E1 & E2) | E3;
C3 = (E1 & E2) | (E3 & E4);

I'd suggest that time model consistent concatenating events like C1 is much
more simple than the one that can accomodate disjunctions like C2 and C3.

It might be, but the requirements contemplate both cases.

Quote:

C1(t) would be true if and only if:
(E1(t0) <= C1(t) <= E1(t1)) &
(E2(t0) <= C1(t) <= E2(t1)) &
(E3(t0) <= C1(t) <= E3(t1))

C2(t) would be true if and only if:
((E1(t0) <= C2(t) <= E1(t1)) &
(E2(t0) <= C2(t) <= E2(t1))) |
(E3(t0) <= C2(t) <= E3(t1))

That sounds like constraint database.

The difficult part is to decide how to best model this into a RDB.

Quote:

My question:

How do you implement this in the context of a relational database? Or you
simply don't? I've been scratching my head for a couple hours now, this
doesn't seem to be my day for it.

For those who wonder what this is about, I'm working on a personnel

training

database. In plain English, the above means: if you have done this and
this and this course, or that one, you are qualified, on this date, to do
job X.

Why time is important at all in this context? If you have done this and
this and this course, or that one, you are qualified disregarding the time.

Because the courses are valid for only a certain period of time
after which you have to retrain. The database holds both current and
historical data.

Thanks & rgs,
Diego Berge.
--
e-mail address invalid, please reply to newsgroups.

#3

"Diego Berge" <dberge (AT) privacy (DOT) net> wrote

Quote:

Why time is important at all in this context? If you have done this and
this and this course, or that one, you are qualified disregarding the
time.

Because the courses are valid for only a certain period of time
after which you have to retrain. The database holds both current and
historical data.

No, I'd still suggest that you can make your model static.

For example, Oracle 8i certification has 4 something exams. If you pass it,
then you are certified oracle 8i dba. You still are certified 8i dba
professional even after 9i is prevalent.

Now, "generic" oracle DBA is time dependendent of course. Yesterday (s)he
was 8i certified professional, and today (s)he must be 9i. But this is much
more simple time dependency.

My apologies for vendor specific example, but I simply have much less
confidence outside of this area. What classes, for example, for certified
java professional are required? Is there such thing as Java Enterprise 1.4
professional? Well, if there is not, then we can introduce it just to follow
the idea of the previous example.

#4

"Diego Berge" <dberge (AT) privacy (DOT) net> wrote

Quote:

My scenario:

Given a series of events E1, E2, ... En occurring in time (so E1 occurs
from
E1(t0) to E1(t1), E2 from E2(t0) to E2(t1) and so on)

Given a series of arbitrary conditions (C) happening at one point (t) in
time, where the conditions are the simultaneous occurrence of a set of (or
combinations of sets of) events E at time t

Examples:

C1 = E1 & E2 & E3;
C2 = (E1 & E2) | E3;
C3 = (E1 & E2) | (E3 & E4);

C1(t) would be true if and only if:
(E1(t0) <= C1(t) <= E1(t1)) &
(E2(t0) <= C1(t) <= E2(t1)) &
(E3(t0) <= C1(t) <= E3(t1))

C2(t) would be true if and only if:
((E1(t0) <= C2(t) <= E1(t1)) &
(E2(t0) <= C2(t) <= E2(t1))) |
(E3(t0) <= C2(t) <= E3(t1))

My question:

How do you implement this in the context of a relational database? Or you
simply don't? I've been scratching my head for a couple hours now, this
doesn't seem to be my day for it.

For those who wonder what this is about, I'm working on a personnel
training
database. In plain English, the above means: if you have done this and
this and this course, or that one, you are qualified, on this date, to do
job X.

Try this Joe Celko post

http://groups.google.co.uk/groups?hl...g.g oogle.com

Regards
Paul Vernon
Business Intelligence, IBM Global Services

#5

Paul Vernon wrote:

Quote:

"Diego Berge" <dberge (AT) privacy (DOT) net> wrote in message

How do you implement this in the context of a relational database?

Try this Joe Celko post

http://groups.google.co.uk/groups?hl...g.g oogle.com

Thanks Paul, that's what I was looking for.

Regards,
Diego Berge.
--
e-mail address invalid, please reply to newsgroups.

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Re: How do you implement this?

comp.databases.theory comp.databases.theory

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Re: How do you implement this? - 09-26-2003 , 10:55 AM