Delete, Truncate, and Drop Commands in SQL: What's the Difference? (Basic 1 - 13)

In SQL, there are three commands that can be used to remove data from a table: DELETE, TRUNCATE, and DROP. Each command has its own unique purpose and behavior, so it is important to understand the difference between them before using them.

DELETE

The DELETE command is used to remove specific rows from a table. It can be used with a WHERE clause to filter the rows that are deleted, or it can be used to delete all rows from the table.

Example:

SQL

DELETE FROM customers WHERE country = 'USA';

This command will delete all rows from the customers table where the country column is equal to USA.

TRUNCATE

The TRUNCATE command is used to remove all rows from a table. It is faster than the DELETE command because it does not need to check for any foreign key constraints or triggers. However, TRUNCATE cannot be rolled back, so it is important to be careful when using it.

Example:

SQL

TRUNCATE TABLE customers;

This command will delete all rows from the customers table.

DROP

The DROP command is used to remove a table from the database. It will also remove all of the table's data, indexes, and privileges. DROP cannot be rolled back, so it is important to be careful when using it.

Example:

SQL

DROP TABLE customers;

This command will drop the customers table from the database.

Which command should I use?

The best command to use depends on your specific needs. If you need to remove specific rows from a table, use the DELETE command. If you need to remove all rows from a table and you are sure that you do not need to roll back the operation, use the TRUNCATE command. If you need to remove a table from the database, use the DROP command.

Here is a table that summarizes the key differences between the DELETE, TRUNCATE, and DROP commands:

| Command | Description | |---|---|---| | DELETE | Removes specific rows from a table. | | TRUNCATE | Removes all rows from a table. | | DROP | Removes a table from the database. |

Conclusion

The DELETE, TRUNCATE, and DROP commands are all powerful tools that can be used to remove data from a database. However, it is important to understand the difference between them before using them, so that you can choose the right command for your needs.