PROBLEM:

While dropping a column on the table, got the below error.(ORA-12984)

SQL> alter table dbatest.ORDER_TAB drop (CREATED);
alter table dbatest.ORDER_TAB drop (CREATED)
                                    *
ERROR at line 1:
ORA-12984: cannot drop partitioning column

REASON:

oerr ora 12984

12984, 00000, “cannot drop partitioning column”
// *Cause: An attempt was made to drop a column used as the partitioning key.
// *Action: This action is not allowed.

We can’t drop the column in a partitioned table if that column is the partitioned key.

1. First, check whether the table is partitioned or not:

SQL> select owner,table_name,partitioned from dba_tables where table_name='ORDER_TAB';

OWNER        TABLE_NAME            PAR
------------ --------------------- ---
DBATEST      ORDER_TAB             YES

2. Find the partitioned key column

SQL>  select owner,name,column_name from dba_part_key_columns where name='ORDER_TAB';

OWNER        NAME         COLUMN_NAME
------------ ------------ -------------
DBATEST      ORDER_TAB    CREATED

Here we can see the column CREATED is the partitioned key column, So oracle is not allowing us to drop that column.