ORDER BY Clause in SQL

The ORDER BY clause in SQL is used to sort the result set of a query in ascending or descending order based on one or more columns. By default, it sorts in ascending order unless specified otherwise.

Key Points

Sorts Query Results:
The ORDER BY clause organizes the returned rows based on the specified column(s) and order (ascending or descending).
Supports Multiple Columns:
You can sort by more than one column, with each column having its own sorting order.

Syntax

SELECT column1, column2, ...
FROM table_name
ORDER BY column1 [ASC|DESC], column2 [ASC|DESC];

ASC: Sorts in ascending order (default).
DESC: Sorts in descending order.

Example

Sorting in Ascending Order (Default)

SELECT first_name, last_name, salary
FROM employees
ORDER BY salary;

Sorts the employees by their salary in ascending order.

Sorting in Descending Order

SELECT first_name, last_name, salary
FROM employees
ORDER BY salary DESC;

Sorts the employees by their salary in descending order.

Sorting by Multiple Columns

SELECT first_name, last_name, department, salary
FROM employees
ORDER BY department ASC, salary DESC;

First sorts the employees by department in ascending order, and within each department, it sorts them by salary in descending order.

Sorting by a Non-Displayed Column

SELECT first_name, last_name
FROM employees
ORDER BY hire_date ASC;

Sorts the employees by their hire_date in ascending order, even though the hire_date column is not displayed in the result.

When to Use the `ORDER BY` Clause

To organize data for better readability.
To rank records based on specific criteria, such as sorting salaries or dates.
To ensure consistent ordering for reporting or pagination in applications.

Note: The ORDER BY clause is always applied after other clauses like WHERE and GROUP BY but before LIMIT or OFFSET.