Oracle: Alter table

The ALTER TABLE statement allows you to rename an existing table. It can also be used to add, modify, or drop a column from an existing table.

Renaming a table

The basic syntax for renaming a table is:

ALTER TABLE table_name
RENAME TO new_table_name;

Adding column(s) to a table

Syntax #1

To add a column to an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
ADD column_name column-definition;

Syntax #2

To add multiple columns to an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
ADD ( column_1 column-definition,
column_2 column-definition,
...
column_n column_definition );

Modifying column(s) in a table

Syntax #1

To modify a column in an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
MODIFY column_name column_type;

Syntax #2

To modify multiple columns in an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
MODIFY ( column_1 column_type,
column_2 column_type,
...
column_n column_type );

Drop column(s) in a table

Syntax #1

To drop a column in an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
DROP COLUMN column_name;

Rename column(s) in a table
(NEW in Oracle 9i Release 2)

Syntax #1

Starting in Oracle 9i Release 2, you can now rename a column.

To rename a column in an existing table, the ALTER TABLE syntax is:

ALTER TABLE table_name
RENAME COLUMN old_name to new_name;

Info source: http://www.techonthenet.com/sql/tables/alter_table.php