[sarunraj]

function strreplace(parent_string varchar2(100), to_replace varchar2(50), replace_by varchar2(50)) return varchar2
as
string1 varchar2(100);
string2 varchar2(100);
final varchar2(200);
begin
string1 = substr(parent_string,1, instr(parent_string,to_replace,1,1) - 1)
string2 = substr(parent_string,length(to_replace) + instr(parent_string,to_replace,1,1), length(parent_string))
final_string = string1||replace_by||string2
return(final_string);
end;

hope this helps,
RaJ