Good, let's get down to work.
You're already pretty skilled when it comes to filtering rows – but have you wondered how they are sorted in the result of an SQL query? Well, the answer is simple – by default, they are not sorted at all. The sequence in which rows appear is arbitrary and every database can behave differently. You can even perform the same SQL instruction a few times and get a different order each time – unless you ask the database to sort the rows, of course.
SELECT * FROM orders ORDER BY customer_id;
In the above example, we've added a new piece: ORDER BY. After this expression, you can simply specify a column on which the data will be sorted.
In this case, we want to sort by the customers' IDs, so we put customer_id in the ORDER BY clause.
Try it yourself. Select all columns from the employees table, and sort the result by the salary.
Type:
SELECT * FROM employees ORDER BY salary;
