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Comparing to NULL
Message
 
 
À
23/07/2007 19:25:47
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Versions des environnements
Visual FoxPro:
VFP 9 SP1
Divers
Thread ID:
01243011
Message ID:
01243024
Vues:
30
>>>
>>>Then wouldn't just a simple IF (VARTYPE(OLDVAL(FIELD(i))<>VARTYPE(EVALUATE(FIELD(i))) be sufficient, or do you need to know when character (or other type) value changes, too?
>>
>>No, this would not work for me. The comparison should work on many different fields. Some fields will change the value but the type will be still be the same. The above expression will not pick up those cases.
>
>If a change in type is detected, that can only be to/from "X" (.NULL.). You could have a secondary check if you need to also know the value has changed (while it remains the same type).

I see. But the following also works (unless you see something I am missing):
IF (!ISNULL(EVALUATE(FIELD(i))) AND ISNULL(OLDVAL(FIELD
(i), "V_V_MYTABLE"))) OR ;
(ISNULL(EVALUATE(FIELD(i))) AND !ISNULL(OLDVAL(FIELD
(i), "V_V_MYTABLE"))) OR ;
!(EVALUATE(FIELD(i)) == OLDVAL(FIELD(i), "V_V_MYTABLE"))
Thank you.
"The creative process is nothing but a series of crises." Isaac Bashevis Singer
"My experience is that as soon as people are old enough to know better, they don't know anything at all." Oscar Wilde
"If a nation values anything more than freedom, it will lose its freedom; and the irony of it is that if it is comfort or money that it values more, it will lose that too." W.Somerset Maugham
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