Comma Separated Values: The Problem with Binding

select nothing
from   this_table
where  this_should_match_one_item in 
          (:this_comma_separated_string);

no rows selected
Trying to bind a variable in-list is a commonly raised problem in Oracle; 
unfortunately an out-of-the box method isn't supplied.

If you want to bind a list of values to a single variable for an “in” comparison, then you need write a PL/SQL function converting it to an array or parse the string in SQL. Tom Kyte goes into details on how to this here.