At 9:38 -0400 10/27/01, jim barchuk wrote:
>> Paul DuBois writes:
>> > NULL basically means "unknown value", so saying WHERE x = NULL cannot
>> > work, even if x is NULL. That means "where one unknown value = another
>> > unknown value", which cannot be evaluated with any certainty. :-)
>> It is sort of odd, though, that x = NULL returns something which
>> appears to be undefined rather than something well-defined
>> (such as false all the time) or an error (which could be said to
>> be well-defined, if errors are considered to be valid responses
>> to queries...).
>Well which would you prefer, false or error? Dealing with errors is
>annoying if not necessary. 'False' is incorrect -if- the field is allowed
>to contain 'nothing' because NULL means it does contain nothing.
I think what Carl meant was that it was strange that the WHERE x = NULL
query returned a non-empty result set. I noticed that in the original
message, too. I don't know what accounts for it.
>ob-filter-words: database table sql