Logical functions
Logical functions test for a condition to evaluate it as true or false. This is known as a Boolean value. If the condition is true, FileMaker Pro returns a 1; if the condition is false, FileMaker Pro returns a 0. You can use the keywords True and False with logical functions and operators when a Boolean value is needed. Keyword True returns 1 and keyword False returns 0.
Logical functions can also evaluate parameters such as text or arithmetic operations that do not make a true or false statement, or in the case of the GetField function, return the contents of another field.
Click a function name for details.
 
Evaluates an expression as a calculation.
1 (true) if data converts to a non-zero numeric value or if a container field holds data; otherwise, returns 0 (false).
1 (true) if a field is empty or other errors occur; otherwise, returns 0 (false).
0 (false) if the data is invalid; otherwise, returns 1 (true).
1 (true) if an expression syntax is correct; otherwise, returns 0 (false).
The next lower or higher value in sourceField when there isn’t a matching related value.
Related topics 
About functions
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Topics in this section
Case
Choose
Evaluate
EvaluationError
ExecuteSQL
GetAsBoolean
GetAVPlayerAttribute
GetField
GetFieldName
GetLayoutObjectAttribute
GetNthRecord
If
IsEmpty
IsValid
IsValidExpression
Let
Lookup
LookupNext
Self