Which operation is NOT performed by the ALTER TABLE statement?

Which operation is NOT performed by the ALTER TABLE statement?

• A. Add a column
• B. Rename a column
• C. Alter a column's data type
• D. Create a new index

Answer: (D)

ALTER TABLE is used to change the structure of an existing table. It can add a new column, rename an existing column, or change a column’s data type, as well as adjust constraints, defaults, and nullability. These actions modify the table’s schema itself. Creating a new index is handled by a separate operation known as indexing, which builds a data structure to speed up data retrieval. While some systems may support index creation in conjunction with table alterations in certain syntax, the standard, portable understanding is that index creation is not the primary function of ALTER TABLE. Therefore, the operation that isn’t performed by ALTER TABLE is creating a new index.

ALTER TABLE is used to change the structure of an existing table. It can add a new column, rename an existing column, or change a column’s data type, as well as adjust constraints, defaults, and nullability. These actions modify the table’s schema itself.

Creating a new index is handled by a separate operation known as indexing, which builds a data structure to speed up data retrieval. While some systems may support index creation in conjunction with table alterations in certain syntax, the standard, portable understanding is that index creation is not the primary function of ALTER TABLE. Therefore, the operation that isn’t performed by ALTER TABLE is creating a new index.