How does the DELETE command function in SQL?

The DELETE command in SQL is used to remove one or more records from a table.

The DELETE command is a Data Manipulation Language (DML) operation that is used to mark the removal of existing records from a table in a relational database management system. It is a powerful command that should be used with caution, as once data is deleted, it cannot be recovered.

The basic syntax of the DELETE command is as follows: DELETE FROM table_name WHERE condition. The table_name is the name of the table where you want to delete data from, and the condition is used to specify which records to delete. If you omit the WHERE clause, all records in the table will be deleted!

For example, if you have a table named 'Students' and you want to delete the record of a student with the ID of 123, you would use the following command: DELETE FROM Students WHERE StudentID = 123. This command will remove the student record where the StudentID is 123.

It's important to note that the DELETE command only removes the data in the table, and not the table itself. If you want to delete the entire table structure along with the data, you would use the DROP TABLE command instead.

In addition, the DELETE command can be used with JOINs and subqueries. For example, you can delete records from one table based on records in another table. This is particularly useful when you want to maintain data integrity across multiple tables.

Lastly, remember that the DELETE command is a transactional operation. This means that you can roll back the deletion if you realise you've made a mistake. However, this is only possible if you haven't committed the transaction yet. Once you commit the transaction, the deleted data is gone for good. Therefore, always be sure about what you're deleting before you execute the DELETE command.