Which SQL clause is used to sort the result set in descending order based on one or more columns?

The SQL clause used to sort the result set in descending order based on one or more columns is the "ORDER BY" clause. Here's how you can use it:

1. First, specify the SELECT statement to choose the data you want to view. For example, if you want to view all data from a table named "Employees", you would start your SQL statement like this:

SELECT * FROM Employees

2. Next, you add the ORDER BY clause, followed by the name of the column you want to sort by. For example, if you want to sort by a column named "LastName", you would add:

ORDER BY LastName

So far, your SQL statement looks like this:

SELECT * FROM Employees ORDER BY LastName

3. By default, the ORDER BY clause sorts data in ascending order. If you want to sort data in descending order, you need to add the DESC keyword. So, to sort the "Employees" table by the "LastName" column in descending order, your SQL statement would look like this:

SELECT * FROM Employees ORDER BY LastName DESC

This SQL statement will return all data from the "Employees" table, sorted by the "LastName" column in descending order.