When two or more relations are joined by logical
operators AND and OR, the program always returns missing if
all of the relations in the expression are missing. However, if any
one of the relations can be determined, the program tries to return
true or false according to the logical outcomes shown in the following
table. The asterisk indicates situations where the program can evaluate
the outcome with incomplete information.
Table 1. Logical outcomes
| Expression |
Outcome |
Expression |
Outcome |
| true AND true |
= true |
true OR true |
= true |
| true AND false |
= false |
true OR false |
= true |
| false AND false |
= false |
false OR false |
= false |
| true AND missing |
= missing |
true OR missing |
= true* |
| missing AND missing |
= missing |
missing OR missing |
= missing |
| false AND missing |
= false* |
false OR missing |
= missing |
|