Modify tables, add columns, delete columns, and modify columns in oracle

Oracle alter table, add column, delete column, modify column 1. add alter table table_name ADD (column datatype [default expr] [, column datatype...]); for example: SQL> ALTER TABLE emp01 ADD eno NUMBER (4); 2. MODIFY the column definition, for example, SQL> ALTER TABLE emp01 MODIFY job VARCHAR2 (15) 2 DEFAULT 'cler' 3. delete a COLUMN, for example, SQL> ALTER TABLE emp01 DROP COLUMN dno; 4. modify the COLUMN name, for example, SQL> ALTER TABLE emp01 RENAME COLUMN eno TO empno; 5. modify the table name, for example, SQL> RENAME emp01 TO employee; 6. add comments such as SQL> comment on table employee IS 'employee information'; SQL> COMMENT ON TABLE employee. name IS 'employee name ';