Returns either result1 or result2, depending on the value of a test.
test - any numeric value or logical expression
result1 - expression or field name
result2 - expression or field name
Data type returned 
text, number, date, time, timestamp, container
Originated in 
FileMaker Pro 6.0 or earlier
If test is True (any non-zero numeric result), FileMaker Pro returns result1. If test is False (0), result2 is returned. Test must be an expression that returns either a numeric or Boolean (True, False) result.
By default, if test refers to a field that doesn’t yet contain a value, If returns an empty result. To override this functionality, deselect the Do not evaluate if all referenced fields are empty checkbox.
If(Country = “USA”;“US Tech Support”;“International Tech Support”) returns International Tech Support, if the Country field contains France or Japan. Returns US Tech Support if the Country field contains USA.
If(State =”CA”;Subtotal * CA Tax Rate;0) returns the tax if the purchaser is a resident of California; otherwise returns 0.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas