character _var is ok
BEGIN
#Routine body goes here...
DECLARE $deltadate int;
DECLARE $deltapart int;
DECLARE $min date;
DECLARE $max date;
SET
$deltadate=DateDiff($Finish,$Start)+1,
$min=If($Start>$From,$Start,$From),
$max=If($Finish<$To,$Finish,$To),
$deltapart=DateDiff($max,$min)+1;
RETURN Round(If($ID,myPrice($Value, $ID, $Start) ,$Value)* $deltapart / $deltadate,0);
END