Question: Is it possible to select the value of the second column using something like an index or column position if i dont know the name of the column? 

```
Select col(2) FROM (
    Select 'a', 'b',' c', 'd' from dual
)

```

Answer: 
If you don't know the name, just give it a nice name ;).

```
Select b FROM (
    Select 'a', 'b' as b, 'c', 'd' from dual
)

```
It is possible in case when you know number of columns in the subquery:

```
SELECT COL2 FROM (
  SELECT NULL COL1, NULL COL2, NULL COL3, NULL COL4 
  UNION ALL 
  select 'a', 'b', 'c', 'd' from dual
) 
WHERE COL2 IS NOT NULL;

```

There are limitations:

* query is hard to read and understand
* you should know number of columns
* value should not be NULL
* not recommended for production use