We can assign a value returned from a select statement to a user-defined variable.
This allows us to refer to it in later statements in the same session.
Those user-defined variables will not persist across sessions.
select @max_price := max(price) from artist; select @max_price;
The max price was assigned to variable @max_price.
If you execute the 2 statements on Toad, the screenshot will look like below: