ORA-12983: cannot drop all columns in a table

Question

Hi,
I am creating a table with two columns.
I have modified a column as unused using ALTER statement.
After that i have tried to drop the another column by using ALTER statement.
But it throws an error ORA-12983: cannot drop all columns in a table.
is it not possible to achieve this via ALTER statement?
thanks

Answer 1

is there any other way to find the name of the columns which have been marked as unused?Don't think so, and you would not be able to do much about. You won't be able to reference it, you won't be able to un-unuse it, and you would even be able to add a new column having same name.
Why are you using SET UNUSED in the first place?
Regards
Peter
Quoting myself:
You won't be able to reference itMaybe not good enough:
SQL> select column_name, data_type, segment_column_id
  from user_tab_cols
where table_name = 'T';
COLUMN_NAME                    DATA_TYPE   SEGMENT_COLUMN_ID
SYS_C00001_11051618:28:14$     NUMBER                      1
B                              NUMBER                      2
SYS_C00003_11051618:28:14$     NUMBER                      3
3 rows selected.
select "SYS_C00003_11051618:28:14$" from t
Error at line 1
ORA-00904: "SYS_C00003_11051618:28:14$": invalid identifier
SQL> alter table t drop column "SYS_C00001_11051618:28:14$";
Table altered.
SQL> select column_name, data_type, segment_column_id
  from user_tab_cols
where table_name = 'T';
COLUMN_NAME                    DATA_TYPE   SEGMENT_COLUMN_ID
B                              NUMBER                      
1 row selected.
Note: Both columns "disappeared"  Thanks MichaelS
Edited by: Peter on May 16, 2011 9:29 AM