Oracle - Can A Bind Variable Be Put In In() Clause If The Variable Can Be Empty

Question

In Oracle, can a bind variable be put in IN() clause if it can be empty? Asking because in the SQL if Oracle see IN() without any data in it, it shows error

ORA-00936: missing expression.

Edit: Failed to mention that no PL/SQL can be used...

Edit2: Also failed to mention that the variable is either in format 1,2,3 or empty string. The empty string cannot be replaced with NULL.

Answer 1

Seems to be working:

declare

   l_statement varchar2(32767);

begin
   l_statement := 'select * from user_tables where table_name in (:a)';

   execute immediate l_statement
      using '';

end;

Answer 2

You can do it, it will be syntactically correct. I hope you are aware that NULL is not equal to anything even to NULL (so NULL=NULL is not TRUE but NULL), it can cause unexpected results in your query, so consider using NVL function if it doesn't affect performance