Please, help me making a good database... 
Author Message
 Please, help me making a good database...

I'd like to create a database to do reporting.

I have two entities?:
the first one is activity with activity code for identification and
activity name for characteristic.
the second one is business with a business coode for identification and
business country for characteristic.

The aim is creating a board were we can find for example, fully-formed
people number in a country for one activity or stike hours number in a
country for one activity.

We have two choice?:

on one hand, we can create a relation between the entities with all
characteristics of training and create an other relation with all
charaacteristics of social climate in a business society.
Thus we have an identification problem?: the training relation have ??
activity code, business code?? for identification and social relation
have ??activity code, business code?? for identification.

To make the difference between those 2 relations, we have to give them a
specific identification code. So we have entities.

We can also create one big relation and put all the characteristics in
it. But it seems more interesting seperate the relation.

On the other hand, we can consider we have entities. Thus, how can we
describe fully-formed people number in a country FOR one activity??

Which is the best solution?? are there any others methods??    


--
Christophe 'Runner' Lesur             Linux

http://www.***.com/ ~runner          &emulation
-------------------------------------------------
The most dangerous path is the middle of the road
-------------------------------------------------



Wed, 14 Feb 2001 03:00:00 GMT
 Please, help me making a good database...

Quote:

>We have two choice :

>on one hand, we can create a relation between the entities with all
>characteristics of training and create an other relation with all
>charaacteristics of social climate in a business society.
>Thus we have an identification problem : the training relation have
>activity code, business code ? for identification and social relation
>have ? activity code, business code ? for identification.

>To make the difference between those 2 relations, we have to give them a
>specific identification code. So we have entities.

If the relationship between the two entites is M:N (Many to
Many), then the correct Relational Datbase Design methodology
is to create a third entity, which has as its primary key (at
least) the primary keys on the other tables.  However that is
the minimum restraint, you can add any number of other
attributes and include them as part of the PK.

+-------------+         +------------+        +-------------+
|             |N        | /         \|      M |             |
| ACTIVITY    +---------+  TRAINING  +--------+   BUSINESS  |
|             |         | \         /|        |             |
+-------------+         +------------+        +-------------+

TRAINING(ACTIVITY_CODE, BUSINESS_CODE, TRAIN_CODE, other_atts);

where ACTIVITY_CODE, BUSINESS_CODE, TRAIN_CODE are the PKs.

Quote:
>We can also create one big relation and put all the characteristics in
>it. But it seems more interesting seperate the relation.

Not a good idea.

Quote:
>On the other hand, we can consider we have entities. Thus, how can we
>describe fully-formed people number in a country FOR one activity ?

Grab a copy of Database Design Studio from www.ChilliSource.com
and try modeling your problem.  You will find it is very easy to
play around and work out what works best.  DDS will take care of
all the PK and FK placements according to your model, so you can
just worry about the entities and relationships.

DDS will also create your schemas for you when you are happy with
the model, so your database will be created exactly as planned.

Lee



Sat, 17 Feb 2001 03:00:00 GMT
 
 [ 2 post ] 

 Relevant Pages 

1. Advice please for making making a database

2. Decision-making tool for best database software

3. COMBO BOX, PLEASE HELP, PLEASE HELP, PLEASE HELP!

4. I need help in designing a school database Please Please help

5. Please help im making insertion faster....

6. locking during index rebuild making db unavailable -- please help

7. Access makes me desperate - Please help me!

8. Please HELP !!!(It makes me crazy)

9. help please! making new records with related fields

10. help for making .cub files with no aggregation please

11. emergency please help me please please please

12. APPROACH QUERY-PLEASE PLEASE PLEASE PLEASE HELP


 
Powered by phpBB® Forum Software