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From:Paul DuBois Date:September 15 2003 4:42pm
Subject:Re: NULL
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At 5:21 PM +0100 9/15/03, Haydies wrote:
>Ye, NULL = "Undefined" in every database I've ever used.
>Null and "" are not equal, NULL and NULL are not equal eigther. Infact
>absolutly nothing is ever equal to NULL.

One slight exception is that for purposes of ORDER BY, GROUP BY, and
DISTINCT, NULL values are considered the same in the sense that they
group together.  (It's difficult to see what other way of handling them
would make sense for such operations.)

>Database/PHP Developer
>----- Original Message -----
>From: "Paul DuBois" <paul@stripped>
>To: "Martin Gainty" <mgainty@stripped>; <rchrismon@stripped>
>Cc: <mysql@stripped>
>Sent: Monday, September 15, 2003 5:02 PM
>Subject: Re: NULL
>: At 11:12 AM -0400 9/15/03, Martin Gainty wrote:
>: >Randy-
>: >
>: >NULL means No Data
>: >So in the case of a MySQL Column defined as Type String
>: >NULL is equivalent to ""
>: Actually, it's not.
>: "" isn't No Data, it's Data with a length of zero.
>: --
>: Paul DuBois, Senior Technical Writer
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Paul DuBois, Senior Technical Writer
Madison, Wisconsin, USA

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NULLMartin Gainty15 Sep
  • Re: NULLPaul DuBois15 Sep
  • Re: NULLHaydies15 Sep
    • Re: NULLPaul DuBois15 Sep