-20019 THE RESULT TYPE RETURNED FROM THE FUNCTION BODY CANNOT BE ASSIGNED TO THE DATA TYPE DEFINED IN THE RETURNS CLAUSE

Explanation
 The data type of the value returned by the function
body must be assignable to the parameter specified in the RETURNS
clause.

System action
 The statement cannot be processed.

Programmer response
 Change the RETURNS type or change the expression
in the RETURN statement so that the result type of the expression
returned from the function body can be made.

SQLSTATE
 42866