Which SQL command is used to discard an entire table from a database?

The command used to discard an entire table from a database is "DROP TABLE." This SQL command completely removes the specified table and all of its data, as well as its structure from the database. Once a table is dropped, it cannot be recovered unless there is a backup available, highlighting the command's irreversible nature.

In comparison, the "DELETE" command removes rows from a table but retains the structure of the table itself, allowing for the potential to insert new data later. "TRUNCATE TABLE" is also used to remove data, but it only removes all rows in a table while keeping the table structure intact, allowing for future data insertion without recreating the table. The "ALTER TABLE" command is utilized to make changes to the structure of an existing table rather than removing it.

Thus, selecting "DROP TABLE" accurately reflects the action of fully discarding a table from the database.