What does the ALTER command do in a database?

The ALTER command in a database is specifically designed to modify the structure of an existing database object, such as a table or a view. This command allows users to make changes, including adding or dropping columns, changing the data type of existing columns, renaming a table, or modifying constraints. For instance, if you want to add a new column to an existing table, you would use the ALTER command to specify the table and the new column definition.

Unlike commands that add data to a table, delete schema, or retrieve data, the ALTER command focuses solely on structural changes. This makes it an essential tool for database administrators and developers who need to refine and update the database schema as requirements evolve.