SELECT * FROM table_name WHERE col_name IS NULL;
See http://www.mysql.com/doc/en/Comparison_Operators.html in the manual for more.
Michael
Miguel Ernesto wrote:
Now that I listen to you Michael, you must probably know how MySQL refers to NULL values on a logical sentence, e.g. If(something=NULL...)
How do I get TRUE on a logical sentence if I want to refer to it as If it is NULL do...?
Thanks on advance, Miguel Ernesto
-----Mensaje original-----
De: Michael Stassen [mailto:[EMAIL PROTECTED] Enviado el: Martes, 07 de Octubre de 2003 17:46
Para: [EMAIL PROTECTED]
Asunto: Re: FW: MySQL not null vs MSAccess required
Cal Evans wrote:
I humbly submit an apology. You are correct. This is a bug (No it is
NOT a feature)
While you may not like it, this definitely is a feature (or an intentional design decision, at least), not a bug. See the docs at <http://www.mysql.com/doc/en/constraint_NOT_NULL.html>. The first line is, "To be able to support easy handling of non-transactional tables, all fields in MySQL have default values." So, if you don't set a default for a column, mysql chooses one for you. With a few exceptions,
NULLable columns default to NULL, NOT NULL columns default to 0 (zero) or '' (empty string). You can change this behavior by building your own
mysql from source with the -DDONT_USE_DEFAULT_FIELDS compile option.
you should be able to define a field as NOT NULL without a default or at the very least, define the default as NULL.
This does not make sense to me. Allowing NULL as the default for a column declared NOT NULL would defeat the purpose of declaring it NOT NULL in the first place.
Michael
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