Alter command Add Column , Drop Column and Modify Column in oracle using | Oracle Alter DDL command
This video explains how to add new column.
This video explains how to modify structure of existing column.
This video explains how to drop existing column permanently.
The ALTER TABLE command in Oracle is used to modify an existing table structure without dropping and recreating it.
You can use this command to add, modify, drop, or rename columns, constraints, and indexes, among other things.