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Problem with foreign key referencing key on same table? - MySQL

I'm quite new to actually designing databases and have come across something I've not done before. Basically one column in a table references another column in the same table and I'm wondering is the correct? destination_id (PK) destination_parent_id (FK ??? as it must take a value from destination_id) destination_name destination_description However the problem I theorectically have is that when I create the first record, destination_parent_id will be looking up a value in destination_id but there will not yet be any value because it is the first record. So are there any ways rounds this? Could I allow destination_parent_id to accept ...

  1. #1

    Default Problem with foreign key referencing key on same table?

    I'm quite new to actually designing databases and have come across something
    I've not done before. Basically one column in a table references another
    column in the same table and I'm wondering is the correct?

    destination_id (PK)
    destination_parent_id (FK ??? as it must take a value from destination_id)
    destination_name
    destination_description

    However the problem I theorectically have is that when I create the first
    record, destination_parent_id will be looking up a value in destination_id
    but there will not yet be any value because it is the first record.

    So are there any ways rounds this? Could I allow destination_parent_id to
    accept a null value as get around?

    Cheers

    Phil


    Phil Guest

  2. #2

    Default Re: Problem with foreign key referencing key on same table?



    On Jan 29, 1:26 pm, "Phil Latio" <co.uk> wrote: 
     

    Yes

    strawberry Guest

  3. #3

    Default Re: Problem with foreign key referencing key on same table?

    >>Could I allow destination_parent_id to accept a null value as get around? 

    After posting this question, I thought how lazy of me and actually tried it
    and on a test table and was surprised my idea (of getting around this
    problem) actually worked.

    Thanks for reconfirming.

    Cheers

    Phil



    Phil Guest

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