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.
 
1 if data converts to a non-zero numeric value; 0 if the specified data has a value of 0 or is empty.
1 if the specified field is empty, if the related field, related table, relationship, or file is missing, or if some other error occurs; otherwise, returns 0.
0 when a record contains an invalid value because of a field type mismatch (text in a date field, for example).
1 if the syntax of the specified expression is correct.
The value specified in the sourceField parameter using the relationships in the relationships graph.
The value specified in the sourceField parameter using the relationships in the relationships graph.
Related topics 
About functions
About formulas
Topics in this section
Case
Choose
Evaluate
EvaluationError
ExecuteSQL
GetAsBoolean
GetField
GetFieldName
GetLayoutObjectAttribute
GetNthRecord
If
IsEmpty
IsValid
IsValidExpression
Let
Lookup
LookupNext
Self