Description of the illustration drop_column_clause.eps

{ SET UNUSED { COLUMN column
             | (column [, column ]...)
             }
  [ { CASCADE CONSTRAINTS | INVALIDATE }... ]
  [ ONLINE ]
| DROP { COLUMN column
       | (column [, column ]...)
       }
  [ { CASCADE CONSTRAINTS | INVALIDATE }... ]
  [ CHECKPOINT integer ]
| DROP { UNUSED COLUMNS
       | COLUMNS CONTINUE
       }
  [ CHECKPOINT integer ]
}