Re: postgresql vs mysql

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От Glen Parker
Тема Re: postgresql vs mysql
Дата
Msg-id 45DF6FC8.9020508@nwlink.com
обсуждение исходный текст
Ответ на postgresql vs mysql  (gustavo halperin <ggh.develop@gmail.com>)
Ответы Re: postgresql vs mysql  (Martijn van Oosterhout <kleptog@svana.org>)
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Ben wrote:
> What I read was that you have no use for NULLs, and that they're
> equivilant to zero or an empty string or some other known value. Sorry
> if I misunderstood that.

Equivalent, yes, because NULL doesn't usually mean UNKNOWN in this
system, just NOT ENTERED.  I do still have use for NULL in data types
that don't inherently have a blank value (numerics, dates, etc.)

I can and do solve the problem by simply not using NULL in character
fields, and by the rather gratuitous use of coalesce() in queries.  The
problem is, it places a burden on people doing ad hoc queries who,
because of the type of data they work with, have no reason to understand
the concept of NULL as it exists in standard SQL.  These aren't computer
scientists, they are accountants and managers.  The result is queries
that either return bad data, or that appear much more complex than
should be required to people who can't see why NULL == zero is NULL.

And as I said, I really don't know what a fully functional solution
would look like, I just know that it would be useful to a large cross
section of users.

-Glen


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