Question

What is the main difference between the SQL commands TRUNCATE, DELETE, and DROP?

a) TRUNCATE is used for deleting records, DELETE removes a table, and DROP clears a database.
b) TRUNCATE is irreversible, DELETE deletes data but not the table, and DROP deletes the entire table.
c) TRUNCATE permanently removes data and structure, DELETE removes data, and DROP removes constraints.
d) TRUNCATE is a DDL command, DELETE is a DML command, and DROP is a DCL command.

Answer 1

TRUNCATE removes all data from a table, DELETE selectively removes rows based on conditions, and DROP deletes the entire table.

Step-by-step explanation:

The main difference between the SQL commands TRUNCATE, DELETE, and DROP is as follows:

1. TRUNCATE: TRUNCATE is used to remove all data from a table, while keeping the table structure intact. It is a faster operation compared to DELETE, as it does not generate undo logs and does not keep a record of the deleted rows. TRUNCATE is an example of a DDL (Data Definition Language) command.
2. DELETE: DELETE removes specific rows from a table based on a specified condition. It can be used to selectively delete data, but it does not delete the entire table. DELETE also generates undo logs, making it slower than TRUNCATE. DELETE is an example of a DML (Data Manipulation Language) command.
3. DROP: DROP deletes an entire table, including both the data and the table structure. It permanently removes the table and all associated data. DROP is also a DDL command.

Therefore, option b) is the correct answer:

• TRUNCATE is irreversible, DELETE deletes data but not the table, and DROP deletes the entire table.