Kbase P86581: Unknown value standard behavior when used in Comparison Operations
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
30/06/2004 |
|
Status: Unverified
GOAL:
Unknown value standard behavior when used in Comparison Operations
FIX:
The question mark is a special character that represents the unknown value. Progress treats a quoted question mark ("?") in a procedure or an input field as a question mark character. It treats an unquoted question mark (?) in a procedure or an input field as an unknown value.
The table below indicates the results when using the unknown value in a comparison expression (EQ, GE, GT, LE, LT, NE). These results are true for both character and integer variables.
Comparison Operator One argument is ? Both arguments are ?
EQ or = F T
GE or >= ? T
GT or > ? F
LE or <= ? T
LT or < ? F
NE or <> T F
Also when using the unknown value in an expression, the result of that expression is usually unknown. For example, when you concatenate first, middle, and last names, and the middle name is ?, then the result is ?.