Kbase 14008: Results of using the unknown value "?" in logical expression
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
Results of using the unknown value "?" in logical expression
How does the use of the unknown value "?" evaluate in a
WHERE clause or other logical expression? First of all,
the unknown value is simply that - unknown. It is neither
true nor false. For example:
DISPLAY (1>?)
yields a result of "?" because it is unknown whether 1 is
greater than the unknown value. Likewise:
DISPLAY (1=?)
yields false. We know that 1 is equal to 1, and but that is
the best we can say without a doubt.
Progress Software Technical Support Note # 14008