On Thu, 23 Oct 2008 10:47:46 +0200 Lysander
Sender: Lysander <***@nowhere.de>
wrote the following in:
Newsgroup: dbase.programming
Post by Glenn Johansenplus returns .t. -------- should this not be false????? the field is not
null, is holds a blank date
What _IS_ an empty date?
I can understand what a NULL date is, because NULL usually means
unknown. But what is an EMPTY date, especially when it comes to the
difference to NULL date?
If you have problems answering this question quick and determined, the
designer of the dBase table rules probably had the same problems.
According to the OLh on "Date amnd time":
An empty date is valid and is represented by empty braces: { }. ( Whatever empty braces are )
According to the OLH on EMPTY():
Use EMPTY( ) to determine if an expression is empty. The definition of empty depends on the type of
the expression:
Expression type: Date Empty if value is: blank date ({ / / })
Conclusion. A blank date is the same as an empty date. When tested with Empty() which does not make
a difference between empty and null the date value may be said to be null.
When using local sql, a blank date may be found with the statement,
select * where <myDateField> is null.
It looks like the designer of the dBase table rules did not have a problem in answering you
question!
Ivar B. Jessen