Which of the SQL command is used to change the structure of a table after it has been created?

Correct option is B

The ALTER command in SQL is used to modify the structure of an existing table. This includes adding, deleting, or modifying columns, renaming a table, or changing column data types after the table has already been created.
Important Key Points:
1. ALTER Command - Used to alter the structure of the database objects like tables. Common uses include adding new columns, modifying existing columns, and dropping columns.
2. Flexibility - The ALTER command provides flexibility to make changes to the schema without dropping and recreating the entire table.
Knowledge Booster:
• UPDATE: The UPDATE command is used to modify the existing data in a table, but it does not change the structure of the table itself.
• DROP: The DROP command is used to delete an entire table or database from the system, including all of its data and structure.
• TRUNCATE: The TRUNCATE command is used to delete all the rows from a table, but it does not affect the table structure. It simply removes all data quickly.