Modifying Table Column


	Lesson 7	Altering a table
	Objective	Modify a table by adding or modifying columns.
		One of the great virtues of a relational database is its flexibility. Once you create a table in your Oracle database, you can change certain aspects of the table with the `ALTER TABLE SQL` command. What the `ALTER TABLE` can and cannot do With the `ALTER TABLE` command, you can change many aspects of an existing table structure. You can: Rename the table Add a column to an existing table Change the attributes of a column, such as the size, data type, or default value of the column Modify the storage characteristics of the table Add or change integrity constraints on the table You can also modify other attributes of a table, such as the partitioning or parallelism associated with the table. The `ALTER TABLE` command, however, cannot drop a column from an existing table. Syntax for `ALTER TABLE` command There is a wide range of syntactical options for the `ALTER TABLE SQL` command, reflecting the many types of modifications you can enact with the command. The basic syntax for the command is shown in the MouseOver below: Alter Table Command The next lesson shows how to delete a table from your Oracle database.