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Learn more about the logical functions AND, OR, NOT, logical values TRUE, FALSE, and the special meta-value UNKNOWN.
Overview
Function / value | Description |
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AND | Returns |
Logic
Tip |
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boolean conditions are evaluated from 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
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TRUE if all its arguments evaluate to TRUE; it returns FALSE if one or more arguments evaluate to FALSE. |
Syntax
Code Block |
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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 FALSE (since the second argument is not equal to TRUE)
OR
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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 |
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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 FALSE (since none of the arguments is TRUE)
UNKNOWN | Use the '?' (question mark), representing UNKNOWN, to check if an expression or an attribute has a value. |
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NOT
This operator reverses the value of its boolean argument.
Syntax
Code Block |
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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
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