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generic sql database copy



  • Hi all!

    I am about to write a generic database copy function. To get the order right, in which the tables must be copied, I need to know about references between tables, so that I copy the referenced table before the referencing table.
    How could I find out, if a table has references?

    Thanks for your time,
    Holger


  • Lifetime Qt Champion

    Hi,

    Most of the databases system have a dump method/helper application that should do the job.

    Is it something like that that you are looking for ?



  • Unfortunately not. My question comes from a different direction: I write a database app with a very specific purpose. I assume, that the schema will have to change from time to time. But my assumption is, that as long as I keep the changes "compatible" - like only adding fields or changing fields from "not null" to "null allowed" it should be OK to create a database with the new schema and copy all existing data - at least for the columns, which exist in the source database.
    So this copy should be a way to keep my databse always compatible with the application.
    Sorry if this sounds complicated. I hope this is clear?

    Thx and best regards
    Holger


  • Lifetime Qt Champion

    In that case, you might want to consider using migrations a bit like Django does so you do not have to take such limitations into account.



  • Not sure, what django refers to, to be honest. But I do not want the user to do anything - the conversion should just happen on the startup of my qt app.
    That's why I search for a solution in Qt. ...


  • Lifetime Qt Champion

    Sorry, the Python Django project. I referred to it as inspiration not as replacement.



  • OK - I got it. I will have a look.
    But I have to admit, that this is the only piece that is missing - everything else I have done before and know how to do - so knowing about the references would really be helpful.
    On the other hand: I might just use pragmas and switch references off - with this I should be able to copy the tables in any order ...

    Anyhow - as always: thanks a lot for your support!


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