Re: protected ON DELETE CASCADE

Murray Hobbs wrote:
>
>i neglected to show it properly
>
>have tables A, B, C, D PLUS a few others
>
>A <- B
>
> F
> |
> v
>A <- C <- D
> ^
> |
> E
>
>i want to delete from C and cascade any delete to E or F but not if
>there are records in D
>
>what i have done is to have ON DELETE CASCADE on C's primary
>
>but force deletes to C through a function that will delete from C only
>if there is no records in D
>
>but i would like to believe there is a better way - a way that does not
>require that i do all my deletes through a function

B REFERENCES A ON DELETE CASCADE
C REFERENCES A ON DELETE CASCADE
D REFERENCES C ON DELETE NO ACTION
E REFERENCES C ON DELETE CASCADE
F REFERENCES C ON DELETE CASCADE

So if there is a deletion in A it cascades to B and C

The deletion in C cascades to E and F, but fails if there is a
reference in D. The failure causes a rollback of the transaction and
thus the deletions in A, B, C, E and F do not happen after all.

--
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
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