Oracle SQL : Retrieving non-existing values from IN clause

Question

Having following query:

select table_name
from user_tables
where table_name in (\'A\',\'B\',\'C\',\'D\',\'E\',\'F\');

Assuming only user_tables

Answer 1

Are you restricted to receiving those values as a comma delimited list?

1. instead of creating a comma delimited list with the source values, populate an array (or a table).
2. pass the array into a pl/sql procedure (or pull a cursor from the table).
3. loop through the array(cursor) and use a dynamic cusror to select count(table_name) from user_tables where table_name = value_pulled.
4. insert into table B when count(table_name) = 0.

5. then you can select all from table B

   select * from tab1;
   ------------------
   A
   B
   C
   D 
   E
   F 
   
   Create or replace procedure proc1 as  
   
   cursor c is select col1 from tab1;
   r tab1.col1%type;
   i number;
   
   begin  
   
   open c;
   loop
     fetch c into r;
     exit when c%notfound; 
     select count(tname) into i from tab where tname = r;
       if i = 0 then 
         v_sql := 'insert into tab2 values ('''||r||''');
         execute immediate v_sql; 
         commit;
       end if; 
   end loop;
   close c;
   end proc1;
   
   select * from tab2;
   ------------------
   A
   D 
   E 
   

if this is not a one-off, then having this proc on hand will be handy.

Answer 2

Only way is to use NOT EXISTS by converting the IN clause String into a Table of values.(CTE)

This is not a clean solution though. As The maximum length of IN clause expression is going to be 4000 only, including the commas..

WITH MY_STRING(str) AS
(
  SELECT q'#'A','B','C','D','E','F'#' FROM DUAL
),
VALUES_TABLE AS
(
  SELECT TRIM(BOTH '''' FROM REGEXP_SUBSTR(str,'[^,]+',1,level)) as table_name FROM MY_STRING
  CONNECT BY LEVEL <= REGEXP_COUNT(str,',')
)
SELECT ME.* FROM VALUES_TABLE ME
WHERE NOT EXISTS
(SELECT 'X' FROM user_tables u
 WHERE u.table_name = ME.table_name);

Answer 3

A good way to generate fake rows is with a standard collection such as sys.odcivarchar2list:

select
    tables_to_check.table_name,
    case when user_tables.table_name is null then 'No' else 'Yes'end table_exists
from
(
    select column_value table_name
    from table(sys.odcivarchar2list('does not exist', 'TEST1'))
) tables_to_check
left join user_tables
    on tables_to_check.table_name = user_tables.table_name
order by tables_to_check.table_name;


TABLE_NAME       TABLE_EXISTS
----------       ------------
TEST1            Yes
does not exist   No

Answer 4

if you have list of all those tables to be checked in Table1 then you can use NOT EXISTS clause

select name
from Table1 T1
where not exists ( select 1 from  
                   user_tables U
                   where T1.name = U.table_name)

Answer 5

You can't. These values have to be entered into a temporary table at the least to do the desired operation. Also Oracle's IN clause list cannot be huge (i.e, not more than 1000 values).