Page History
...
| Tip |
|---|
| Boolean conditions are evaluated from the left to the right. There is no order for the logical operators. Use parentheses to create hierarchy in your logical expressions. Example: TRUE OR (TRUE AND FALSE) will evaluate (TRUE AND FALSE) first. |
AND
This function returns TRUE if all its arguments evaluate to TRUE; it returns FALSE if one or more arguments evaluate to FALSE.
Syntax
| Code Block |
|---|
argument1 AND argument2 [AND ...] |
- argument1 - The first boolean condition that you want to evaluate.
- argument2 - The first boolean condition that you want to evaluate.
- [AND …] - Additional boolean conditions that you want to evaluate.
Return type
- boolean
Examples
- TRUE AND TRUE results in TRUE
- TRUE AND FALSE results in FALSE
- TRUE AND ? (= UNKNOWN) results in UNKNOWN
OR
This function returns TRUE if at least one of its arguments evaluates to TRUE; it returns FALSE if none of the arguments evaluate to TRUE.
Syntax
| Code Block |
|---|
argument1 OR argument2 [OR ...] |
argument1 - The first boolean condition that you want to evaluate. argument2 - The first boolean condition that you want to evaluate. [OR …] - Additional boolean conditions that you want to evaluate.
Return type
- boolean
Examples
- TRUE OR TRUE results in TRUE
- TRUE OR FALSE results in TRUE
- TRUE OR ? (= UNKNOWN) results in TRUE
- FALSE OR ? (= UNKNOWN) results in UNKNOWN
TRUE
This is the boolean value TRUE.
FALSE
This is the boolean value FALSE.
NOT
This operator reverses the value of its boolean argument.
Syntax
| Code Block |
|---|
NOT argument |
- argument - The boolean condition of which you want to reverse its value.
Return type
- boolean
Examples
- NOT (TRUE) results in FALSE
- NOT (TRUE AND FALSE) results in TRUE
- NOT (? (= UNKNOWN)) results in UNKNOWN
- NOT (NOT (TRUE)) results in TRUE
UNKNOWN
You can use the '?' (question mark), representing UNKNOWN, to check if an expression or an attribute has a value.
Example
Suppose a model with an entity Person and attributes Person.name and Person.age. In runtime, a user fills out a form and enters his name, but forgets to fill out his age.
As a result
- Person.name = ? returns FALSE since this attribute is filled out
- Person.age = ? returns TRUE since this attribute is not filled out and therefore is UNKNOWN
Overview
Content Tools