I am stuck in normalization

[lasta]

Hi everybody.
I am really stuck in normalization.
I am writing a program which will make working process of one firm easier.
I have a table with information about "press forms", used in working process. They are used in producing different goods.
I have made a unique field 'kod' in this table to use it as primary key in relations. So in other tables where I work with "press form" I simply add a foreign key.
But later I found out that there exist a special group of "press forms" that have some extended unique properties
I don't have in my "press form" table. In order to solve this problem I simply add some new fields in "press form" so that both new and old "press form" where discribed.
BUT as "normalization says" I must separate these new "press froms" into separate table. But in this case I didn't find out how to organaze relations among other tables.

I am waiting for your advices.
lasta

 

[Oppenhiemer]

Hi Lasta -

Not abxolutely sure I understand, but here is my understanding :

You have an entity (table) called "Press Form". You want to create new tables that inherit the properties of "press Form" but the new tables (entities) may include other unique fields (not found in the original table.) Am I right so far ?

Anyway, without knowing the implications of the new fields - I would assume the new new tables would inherit the relationships that existed in the original table ?

Maybe you could post with more info (in case I have not unserstood .)

Opp.

 

[lasta]

I'll try to explain once more.
Each good has it's own press_form used in producing process.
Due to normalization I have made a special table(entity) "press_form" in order to store all needed info about press_forms : size, name, weight, length, etc.(I've got about 50 params). Also I added a special field 'kod' in order to use it in relations.
In all other tables I have added a foreign key(press_form_kod) references press_form(kod).
That means that ALL the press_forms MUST be stored in "press_form" table.
But also there exists a group of press_forms which have it's own params( about 10 params) and they don't have the magiority of params that already exist in my press_form table, so I simply have added 10 more params into press_form table.
BUT THAT IS NOT A normalization.
Due to normalization I must separate this group of press_forms into separate table.
In this case I don't know how to build relations among the tables of my database. (
I cannot make this:
Table1.A is referenced to Table2.B or to Table3.c.
I cannot make a 'unioun' operation.
).
If something is still unclear please write me.
This problem is of great importance to me.
lasta.

 

[Oppenhiemer]

Still not 100% clear on problem details Im afraid lasta. But it does sound like you have 3 disctinct entities (even though one is primarily derived from the other.)

Sorry I cant help with this one.

Opp.

 

[Oppenhiemer]

Still not 100% clear on problem details Im afraid lasta. But it does sound like you have 3 disctinct entities (even though one is primarily derived from the other.)

Sorry I cant help with this one. May be worth posing on the General database discussion group here forum669

 

[lasta]

That's ok Opp.
English is not my native language and I cannot explain my problem quite well.
I'll try to fing out the nest solution by myself.
that's for your trying to help.
lasta