CREATE PROCEDURE (IN...)
BEGIN
DECLARE ret_code
...UPDATE SOMETHING....
SELECT ret_code as return_code from dual;
END

CREATE PROCEDURE (IN...)
BEGIN
DECLARE returnVal
if(conditional true)
    ..Update something else..
    Set returnVal = x;
else
    call proc1(var1,...)
    Set returnVal = (ret_code obtained from proc1)
end if
select returnVal;
END

CREATE FUNCTION (...) RETURNS ...datatype...
BEGIN
DECLARE ret_code
...UPDATE SOMETHING....
RETURN ret_code;
END

CREATE FUNCTION (...) RETURNS ...datatype...
BEGIN
DECLARE returnVal
if(conditional true)
    ..Update something else..
    Set returnVal = x;
else
    Set returnVal = proc1(var1,...)
end if
RETURN returnVal;
END

CREATE PROCEDURE (OUT ret_code ...datatype..., IN...)
BEGIN
...UPDATE SOMETHING....
Set ret_code = return_code;
END

CREATE PROCEDURE (OUT returnVal ...datatype..., IN...)
BEGIN
if(conditional true)
    ..Update something else..
    SET returnVal = x;
else
    call proc1(returnVal, var1,...)
end if
END