IDENTITY COLUMN FOR AUTO GENERATED NUMBER IN ORACLE 12C (FROM BANGLADESH)
The identity column is very useful for the surrogate primary key column. When you insert a new row into the identity column, Oracle auto-generates and insert a sequential value into the column.
....................Identity Column Structure...........
GENERATED [ ALWAYS | BY DEFAULT [ ON NULL ] ] AS IDENTITY [ ( identity options ) ]
1. GENERATED ALWAYS AS IDENTITY
2. GENERATED BY DEFAULT AS IDNENTITY
3. GENERATED BY DEFAULT ON NULL