DB2中一个全角到半角的转换函数

create function conv(input varchar(100))
returns varchar(100)
begin atomic
declare i integer;
declare code integer;
declare str varchar(100);
set i=1;
set str='';
while i<length(input) do
set code=ascii(substr(input,i,1));
if(code=163) then
set str=str||chr(ascii(substr(input,i+1,1))-128);
set i=i+2;
else
set str=str||substr(input,i,1);
set i=i+1;
end if;
end while;
return str;
end@