SQL String formatting - help

Question

I have a simple sql statement that works (in my case, returns 28 rows).
select columna,
columnb
from table
where columnb in ('Value1','Value2')
Next, I can do something like:
select ''''||replace('Value1,Value2',',',''',''')||'''' from dual and it returns a string:
(''''||REPLACE('VALUE1,VALUE2',',',''',''')||'''')
'Value1','Value2'
What I would like to do, is combine the two statements because the "in" statement will depend on a comma separated value list that the user will supply (which is why I'm trying to format it as an "in" statement would be formatted)
I've tried:
select columna,
columnb
from table
where columnb in (select ''''||replace('Value1,Value2',',',''',''')||'''' from dual);
This SQL statement returns 0 rows instead of my 28 that I think I should get. What am I doing wrong?

Answer 1

You may want to use Dynamic SQL, since the "in" list needs to be built each time:
SQL> var cr refcursor
SQL>
SQL> declare
2 v_first_char varchar2(100);
3 v_qry varchar2(1000);
4 begin
5 v_first_char := ''''||replace('&first_char',',',''',''')||'''';
6 v_qry := 'select empno,ename from emp where substr(ename,1,1) in ('||v_first_char||')';
7 open :cr for v_qry;
8 end;
9 /
Enter value for first_char: A
PL/SQL procedure successfully completed.
SQL> print cr
EMPNO ENAME
7499 ALLEN
7876 ADAMS
SQL>
SQL> /
Enter value for first_char: A,J
PL/SQL procedure successfully completed.
SQL> print cr
EMPNO ENAME
7499 ALLEN
7566 JONES
7876 ADAMS
7900 JAMES
SQL>
SQL>