Database Diagram Cardinality in 11g

Question

I am creating a database diagram in jdev 11g, I can drop foreign key relationships between the table objects, but they always default to * to 0..1
and I can't seem to see a way to change the cardinality. Anyone know how this is done.
Orlando

Answer 1

Hi,
It depends which method you are using to create the FK and the makeup of the underlying columns of the key
Also depends which is your 'source' and 'target' table (when drawing the FK or dragging columns) - source is the '1' side and target is the 'm'
Using the diagrammer you cannot explicitly select the FK line and change the cardinality
Try doing the following in the diagram and see the differences in cardinality:
1. create 2 tables (a, b) with no PK defined
select the FK object in the drawing palette -click on a and drag to b
the Create FK dialog opens and you can create a PK based on any col in 'a' and the same col in 'b' will be used as the FK column (if it doesn't exist in 'b' it will be created.
This is 0..1:M
2. select the FK line and delete it
mark what was the FK column in 'b' as 'connot be null'
select the FK object - again drag from 'a' to 'b'
same FK is created - but this time, as FK column in 'b' is not null - cardinality is 1:m
3. delete the FK again
select the PK reference in 'a' and drag it to 'b'
FK is created in 'b' - 0..1:m and a new column is created for the FK
but if you double click on the FK in 'b' and change the Local Column to the original FK column (that is not null) the cardinality will change to 1:m
(note - click next to col name and a dropdown will appear to allow you to select another column)
4. delete the FK and also delete the PK from 'a'
select a column from 'a' and drag to 'b'
UK is created in 'a' and a FK in 'b' with 0..1:m cardinality
Hope this helps
rgds
Susan