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From:Jeremy Cole Date:May 1 2007 1:12am
Subject:Re: IS NULL Question
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Hi John,

Are you sure they are actually NULL and not "NULL" (i.e. the string "NULL")?

Try this:

SELECT first, last, ISNULL(suffix), LENGTH(suffix) FROM persons LIMIT 5;

Regards,

Jeremy

John Kebbel wrote:
> I'm having problems understanding NULL. I grasp what a NULL value is,
> but I can't get NULL to perform correctly. For instance, if I do a
> Select statement, I see that I have columns with a NULL value.
> 
> select first, last, suffix  from persons LIMIT 5;
> +-----------+----------+--------+
> | first     | last     | suffix |
> +-----------+----------+--------+
> | Benjamin  | Page     | NULL   |
> | Jonathan  | Watson   | NULL   |
> | Jose      | Thorson  | NULL   |
> | Alejandro | Nickels  | NULL   |
> | Griselda  | Richards | NULL   |
> +-----------+----------+--------+
> 5 rows in set (0.01 sec)
> 
> Logically, it seems that a Select statement should find these five plus
> any other NULL values in the suffix column. However, such a select
> statment returns an empty set.
> 
> mysql> select first, last, suffix  from persons where suffix IS NULL;
> Empty set (0.00 sec)
> 
> Does anyone see what I'm doing wrong? (Thanks in advance for any help.)
> 
> 
> 
> 

-- 
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www.provenscaling.com
Thread
IS NULL QuestionJohn Kebbel1 May
  • Re: IS NULL QuestionJeremy Cole1 May
    • Re: IS NULL QuestionJohn Kebbel1 May
  • Re: IS NULL QuestionMartijn Tonies1 May
    • Re: IS NULL QuestionLucas.CTR.Heuman1 May
  • Re: IS NULL QuestionKevin Hunter1 May
    • Re: IS NULL QuestionGerald L. Clark1 May
      • Re: IS NULL QuestionKevin Hunter1 May
    • RE: IS NULL QuestionJerry Schwartz1 May
      • Re: IS NULL QuestionBaron Schwartz1 May
    • batch modeCharles Brown2 May
      • Re: batch modeMogens Melander2 May
        • Re: batch modeMogens Melander2 May