Where mydate>= "2011/04/01"::date and mydate<= "2011/04/30"::date
With the above where will the NULL's be selected????
Here is what I get when I try:
spi=> SELECT NULL::DATE>= '2011-04-01'::DATE AND NULL::DATE<=
'2011-04-30'::DATE;
?column?
----------
(1 row)
spi=> SELECT (NULL::DATE>= '2011-04-01'::DATE AND NULL::DATE<=
'2011-04-30'::DATE) IS TRUE;
?column?
----------
f
(1 row)
spi=> SELECT (NULL::DATE>= '2011-04-01'::DATE AND NULL::DATE<=
'2011-04-30'::DATE) IS FALSE;
?column?
----------
f
(1 row)
spi=> SELECT (NULL::DATE>= '2011-04-01'::DATE AND NULL::DATE<=
'2011-04-30'::DATE) IS UNKNOWN;
?column?
----------
t
(1 row)
Sorry Richard, I do not understand.
It looks like you are saying the NULLS will be returned too
As a summary:
============================================
(1)
null:date COMPARE 'real date'::DATE
Will always return NUll, so you will not get the record returned at all!
(2) examples he provided:
. (null:date COMPARE 'real date'::DATE) IS NULL;
. (null:date COMPARE 'real date'::DATE) IS UNKNOWN;
Null returns true.
(3) null is true/false;
returns false
Emi
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