Scalar functions can accept zero or more input parameters.
Syntax for Creating Scalar Functions
CREATE FUNCTION [ owner_name. ] function_name
( [ { @parameter_name scalar_parameter_data_type [ = default ] } [ ,...n ] ] )
RETURNS scalar_return_data_type
[ WITH { ENCRYPTION | SCHEMABINDING } [,...n] ]
[ AS ]
BEGIN
function_body
RETURN scalar_expression
END