Hi all,
I'm setting up a DB in which ( besides normal relations ) an
AND/OR-relation is to be stored:
I have two tables "documents" and "atoms", where a document shall
"depend" upon a logical expression of atoms.
e.g. (please widen your window for this)
###########################################################################################
### ###
### document1 "depends" on (atom1 OR atom2) AND (atom1 OR atom3 OR
atom4) AND (atom5) ###
### ###
###########################################################################################
This is after some normalization - I could also have (.. AND ..) OR (..
AND ..)
I don't have NOT's.
My idea is to have have two extra-tables:
CREATE TABLE or_groups(
id ... primary key,
document_id ... references documents
);
CREATE TABLE dependencies(
or_id ... references or_groups,
atom_id ... references atoms
);
with ( mapping the example )(please widen your window for this)
| documents | | or_groups |
| id | name | | id | document_id |
| 1 | document1 | | 1 | 1 |
| | | | 2 | 1 |
| | | | 3 | 1 |
| dependencies | | atoms |
| or_id | atom_id | | id | name |
| 1 | 1 | | 1 | atom1 |
| 1 | 2 | | 2 | atom2 |
| 2 | 1 | | 3 | atom3 |
| 2 | 3 | | 4 | atom4 |
| 2 | 4 | | 5 | atom5 |
| 3 | 5 | | | |
Because I'm a novice in Databases and the idea was pure naive intuition
I want to ask, whether this is a standard problem and whether there is a
standard solution.
Am I running into problems ?
Do bad things happen when "documents" and "atoms" are the same table ?
Greetings and Thanx Fritz
