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From:Gerald Clark Date:August 13 2002 1:12pm
Subject:Re: NULL values -- expected behavior or bug?
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Empty strings are NOT nulls.
They are just  zero length strings.

Aron Pilhofer wrote:

>>Changing the column to allow NULL doesn't mean that any of the existing
>>values will be *changed* to NULL.  That seems to be what you're expecting,
>>but why?
>No, no. Maybe I didn't explain well enough. The fields in question contained
>NULL values from the beginning, when I populated them, even though the
>fields were set up not to allow NULLs. Is that clearer?
>If I had set up the table correctly from the beginning, there would be some
>records with values, some with NULLs, in a field formatted to accept either
>one. Since I didn't, one would think the insert would fail or something like
>that -- but it didn't. MySQL populated the table just fine. And since NULLs
>weren't allowed, it must have assigned some kind of invisible placeholder
>value or something in those instances. I know it did something along these
>lines because a count() should not have included NULLs, but it did. And a
>select should of NULLs should have produced results, but it didn't.
>I realized my mistake, went back and fixed the field, but the count() and
>select still produced the same results. Those placeholder values (and I'm
>just guessing here that's what's going on) are not stripped out.
>The bottom line is this: If you create a field in which there will be NULL
>values, you *must* create the table to allow NULLs from the beginning, even
>though inserts and such appear to work. You cannot change the field to allow
>NULLs after the fact and expect it to work correctly.
>What I am wondering is whether this is the expected, correct behavior or a
>bug? Also, if there's any workaround that makes those blanks into true
>Hope that's clearer. Thanks in advance!
>: Aron Pilhofer
>: Director, Campaign Finance Information Center
>: Investigative Reporters and Editors
>: National Institute for Computer-Assisted Reporting
>: Phone: (202) 362-3223
>: Email: aron@stripped
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fulltext index update crashRyan Barber12 Aug
  • NULL values -- expected behavior or bug?Aron Pilhofer12 Aug
    • Re: NULL values -- expected behavior or bug?Paul DuBois12 Aug
      • RE: NULL values -- expected behavior or bug?Aron Pilhofer12 Aug
        • Re: NULL values -- expected behavior or bug?Gerald Clark13 Aug
    • Re: NULL values -- expected behavior or bug?Keith C. Ivey12 Aug
  • Re: fulltext index update crashSergei Golubchik12 Aug