Re: protected ON DELETE CASCADE

ok *click* i get it i get it

m

Oliver Elphick wrote:
>
> 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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