FAQ
Hello,
is it necessary to have a full column reserved for the class qualifier in case of single table inheritance?
I.e. instead of qualifier
personType = 'CUSTOMER'
would something like
personType like 'C%'
work? Anyone tried such a thing yet?
Thanx in advance,
Péter

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  • Mike Kienenberger at Feb 27, 2007 at 2:25 pm
    I've not used single-table inheritance, but I'm pretty sure the
    qualifier is just a qualifier and completely independent of columns.

    It could be "0 = mod(random(), 2)" if the database supported the functions.

    In this case, the fastest thing to do is to just test your alternate qualifier.
    On 2/27/07, Török Péter wrote:


    Hello,
    is it necessary to have a full column reserved for the class qualifier in
    case of single table inheritance?
    I.e. instead of qualifier
    personType = 'CUSTOMER'
    would something like

    personType like 'C%'
    work? Anyone tried such a thing yet?
    Thanx in advance,
    Péter
  • Andrus Adamchik at Feb 27, 2007 at 2:39 pm
    This works. But of course it is up to the programmer to ensure that
    the qualifier is built in such a way that multiple subclasses do not
    overlap.

    Andrus

    On Feb 27, 2007, at 4:24 PM, Mike Kienenberger wrote:

    I've not used single-table inheritance, but I'm pretty sure the
    qualifier is just a qualifier and completely independent of columns.

    It could be "0 = mod(random(), 2)" if the database supported the
    functions.

    In this case, the fastest thing to do is to just test your
    alternate qualifier.
    On 2/27/07, Török Péter wrote:


    Hello,
    is it necessary to have a full column reserved for the class
    qualifier in
    case of single table inheritance?
    I.e. instead of qualifier
    personType = 'CUSTOMER'
    would something like

    personType like 'C%'
    work? Anyone tried such a thing yet?
    Thanx in advance,
    Péter
  • Michael Gentry at Feb 27, 2007 at 2:29 pm
    I've not actually tried that, but I wouldn't really advise it if it
    did work. Could lead to unexpected problems down the road, such as
    another personType starting with a "C", etc. It might be interesting
    to try it, though, just to see how it worked. :-)

    /dev/mrg

    On 2/27/07, Török Péter wrote:


    Hello,
    is it necessary to have a full column reserved for the class qualifier in
    case of single table inheritance?
    I.e. instead of qualifier
    personType = 'CUSTOMER'
    would something like

    personType like 'C%'
    work? Anyone tried such a thing yet?
    Thanx in advance,
    Péter

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postedFeb 27, '07 at 2:22p
activeFeb 27, '07 at 2:39p
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