Re: NULL vs. Empty String

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От Oliver Elphick
Тема Re: NULL vs. Empty String
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Msg-id 200103140656.f2E6unG27646@linda.lfix.co.uk
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Ответ на NULL vs. Empty String  (David Wheeler <david@wheeler.net>)
Ответы Re: NULL vs. Empty String
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David Wheeler wrote:
  >Is there a way to get Posgres to assume that a '' insert should be a NULL
  >insert? And if not, does anyone know of a way to get mod_perl to make that
  >assumption instead?

You could write a rule for each table/column that would substitute
NULL for ''.

However, the concept is all wrong.  NULL means "I don't know what
this value is". '' means "I know that this value is an empty string".
Furthermore, having NULLs in columns means you have to be careful
to use ternary logic for every condition (because NULL=x is neither
true nor false).

--
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
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