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INF: Cascade-to-Null relations are supported in JET 4

Discussion in 'Information Technology' started by Allen Browne, Jul 28, 2006.

  1. Allen Browne

    Allen Browne
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    Guest

    In Access 2000 and later, you can create a relation between tables where
    related records can be automatically set to Null rather than deleted when
    the primary record is deleted.

    I have not seen anyone using or discussing this feature, so there is a new
    article explaining the concept here:
    Cascade to Null Relations
    at:
    http://allenbrowne.com/ser-64.html

    --
    Allen Browne - Microsoft MVP. Perth, Western Australia.
    Tips for Access users - http://allenbrowne.com/tips.html
    Reply to group, rather than allenbrowne at mvps dot org.
     
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  3. polite person

    polite person
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    On Sat, 15 Jul 2006 10:05:42 +0800, "Allen Browne" <AllenBrowne@SeeSig.Invalid> wrote:

    >In Access 2000 and later, you can create a relation between tables where
    >related records can be automatically set to Null rather than deleted when
    >the primary record is deleted.
    >
    >I have not seen anyone using or discussing this feature, so there is a new
    >article explaining the concept here:
    > Cascade to Null Relations
    >at:
    > http://allenbrowne.com/ser-64.html


    Allen, can this be done in a similar way in SQL-server? Will upsizing handle it?
     
  4. Allen Browne

    Allen Browne
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    Guest

    Haven't experimented.

    Perhaps someone who has can comment.

    --
    Allen Browne - Microsoft MVP. Perth, Western Australia.
    Tips for Access users - http://allenbrowne.com/tips.html
    Reply to group, rather than allenbrowne at mvps dot org.

    "polite person" <snip@snippers.com> wrote in message
    news:qalhb29fcbu31e3fmsljp96ebsvh15c64v@4ax.com...
    > On Sat, 15 Jul 2006 10:05:42 +0800, "Allen Browne"
    > <AllenBrowne@SeeSig.Invalid> wrote:
    >
    >>In Access 2000 and later, you can create a relation between tables where
    >>related records can be automatically set to Null rather than deleted when
    >>the primary record is deleted.
    >>
    >>I have not seen anyone using or discussing this feature, so there is a new
    >>article explaining the concept here:
    >> Cascade to Null Relations
    >>at:
    >> http://allenbrowne.com/ser-64.html

    >
    > Allen, can this be done in a similar way in SQL-server? Will upsizing
    > handle it?
     
  5. Sky

    Sky
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    Guest

    Re: Cascade-to-Null relations are supported in JET 4

    If you permit changes to the parent key field, perhaps you need:
    dbRelationCascadeNull + dbRelationUpdateCascade
    to enable the equivalent of:
    On Update Cascade, On Delete Set Null


    - Steve

    "Allen Browne" <AllenBrowne@SeeSig.Invalid> wrote in message
    news:44b84d7b$0$21696$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
    > In Access 2000 and later, you can create a relation between tables where
    > related records can be automatically set to Null rather than deleted when
    > the primary record is deleted.
    >
    > I have not seen anyone using or discussing this feature, so there is a new
    > article explaining the concept here:
    > Cascade to Null Relations
    > at:
    > http://allenbrowne.com/ser-64.html
    >
    > --
    > Allen Browne - Microsoft MVP. Perth, Western Australia.
    > Tips for Access users - http://allenbrowne.com/tips.html
    > Reply to group, rather than allenbrowne at mvps dot org.
    >
     
  6. Allen Browne

    Allen Browne
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    Guest

    Re: Cascade-to-Null relations are supported in JET 4

    Thank you Sky.

    That is correct if you want cascading updates as well as cascading deletes.

    --
    Allen Browne - Microsoft MVP. Perth, Western Australia.
    Tips for Access users - http://allenbrowne.com/tips.html
    Reply to group, rather than allenbrowne at mvps dot org.

    "Sky" <sky@NOSPAMstanleyassociates.com> wrote in message
    news:9odug.649$rT6.404@trnddc03...
    > If you permit changes to the parent key field, perhaps you need:
    > dbRelationCascadeNull + dbRelationUpdateCascade
    > to enable the equivalent of:
    > On Update Cascade, On Delete Set Null
    >
    > - Steve
    >
    > "Allen Browne" <AllenBrowne@SeeSig.Invalid> wrote in message
    > news:44b84d7b$0$21696$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
    >> In Access 2000 and later, you can create a relation between tables where
    >> related records can be automatically set to Null rather than deleted when
    >> the primary record is deleted.
    >>
    >> I have not seen anyone using or discussing this feature, so there is a
    >> new article explaining the concept here:
    >> Cascade to Null Relations
    >> at:
    >> http://allenbrowne.com/ser-64.html
     
  7. RoyVidar

    RoyVidar
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    Guest

    "polite person" <snip@snippers.com> wrote in message
    <qalhb29fcbu31e3fmsljp96ebsvh15c64v@4ax.com>:
    > On Sat, 15 Jul 2006 10:05:42 +0800, "Allen Browne"
    > <AllenBrowne@SeeSig.Invalid> wrote:
    >
    >> In Access 2000 and later, you can create a relation between tables
    >> where related records can be automatically set to Null rather than
    >> deleted when the primary record is deleted.
    >>
    >> I have not seen anyone using or discussing this feature, so there is
    >> a new article explaining the concept here:
    >> Cascade to Null Relations
    >> at:
    >> http://allenbrowne.com/ser-64.html

    >
    > Allen, can this be done in a similar way in SQL-server? Will upsizing
    > handle it?


    The feature, as far as I've understood, was introduced in SQL Server
    2005. So it should be available there. DDL through ADO seems to work,
    I haven't tested other approaches.

    --
    Roy-Vidar
     
  8. Jamie Collins

    Jamie Collins
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    Guest

  9. Pieter Wijnen

    Pieter Wijnen
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    Guest

    because we're all sensible enough to program cascading deletes <g>

    Pieter

    "Jamie Collins" <jamiecollins@xsmail.com> wrote in message
    news:1153146778.088558.124710@h48g2000cwc.googlegroups.com...
    >
    > Allen Browne wrote:
    >> I have not seen anyone using or discussing this feature

    >
    > That's funny, I have:
    >
    > http://groups.google.com/group/micr...esdbdesign/browse_frm/thread/2b8601b4391581d/
    >
    > lol!
    >
    > Jamie.
    >
    > --
    >
     
  10. Pieter Wijnen

    Pieter Wijnen
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    Guest

    because we're all sensible enough to program cascading deletes <g>

    Pieter

    "Jamie Collins" <jamiecollins@xsmail.com> wrote in message
    news:1153146778.088558.124710@h48g2000cwc.googlegroups.com...
    >
    > Allen Browne wrote:
    >> I have not seen anyone using or discussing this feature

    >
    > That's funny, I have:
    >
    > http://groups.google.com/group/micr...esdbdesign/browse_frm/thread/2b8601b4391581d/
    >
    > lol!
    >
    > Jamie.
    >
    > --
    >




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  11. Jamie Collins

    Jamie Collins
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    Guest

    Pieter Wijnen wrote:
    > because we're all sensible enough to program cascading deletes <g>


    AFAIK for Access/Jet using ON DELETE CASCADE is the only way of doing
    so as a single atomic action.

    As someone said, 'Trust the engine, Luke.'

    Jamie.

    --
     
  12. Pieter Wijnen

    Pieter Wijnen
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    Guest

    that's true

    Pieter

    "Jamie Collins" <jamiecollins@xsmail.com> wrote in message
    news:1153209852.748751.305290@m73g2000cwd.googlegroups.com...
    >
    > Pieter Wijnen wrote:
    >> because we're all sensible enough to program cascading deletes <g>

    >
    > AFAIK for Access/Jet using ON DELETE CASCADE is the only way of doing
    > so as a single atomic action.
    >
    > As someone said, 'Trust the engine, Luke.'
    >
    > Jamie.
    >
    > --
    >




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