Alter Table Tablename and Drop Columns

ALTER TABLE tablename SET UNUSED 
(COLUMN  columnname | (col1, col2, ...) )
[CASCADE CONSTRAINTS | INVALIDATE];

ALTER TABLE tablename DROP 
(COLUMN  columnname | (col1, col2, ...) | UNUSUED COLUMNS)
[CASCADE CONSTRAINTS |INVALIDATE];
ALTER TABLE STORM_TRACK SET UNUSED (LAT,LON);
ALTER TABLE STORM_TRACK DROP UNUSED COLUMNS;
ALTER TABLE SHIPPING ACTION DROP COLUMN LOG_TIME;

SET UNUSED	After setting a column as unused, it does not appear in the `DESC` command, or in `SELECT *` queries.
[CASCADE CONSTRAINTS \| INVALIDATE]	`CASCADE CONSTRAINTS` must be used if a constraint contains a combination of used and unused columns.
INVALIDATE	`INVALIDATE` causes Oracle to invalidate objects that depend on the dropped or unused column(s), such as views. Currently, this is always done, whether or not you specify the `INVALIDATE` keyword.