What does the ALTER TABLE statement do in SQL?

The ALTER TABLE statement in SQL is specifically designed to modify the structure of an existing table. This command allows database administrators and developers to perform various operations such as adding new columns, deleting existing columns, changing the data type of a column, or setting up constraints like primary keys and foreign keys.

For instance, if you need to add a new attribute to a table to capture additional information, the ALTER TABLE statement would be the appropriate command to accomplish this without needing to recreate the table and lose existing data. Understanding this functionality is crucial for managing and adapting databases to changing application requirements while ensuring data integrity and performance.

In contrast, other actions such as deleting tables, creating new ones, or retrieving data are handled by different SQL commands (e.g., DROP TABLE, CREATE TABLE, and SELECT, respectively), which do not alter the structure of existing tables.