4.3 ORDER BY clause

 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. It is often used with the SELECT statement to present the data in a more organized and meaningful way.

4.3.1 Basic Syntax

The basic syntax of the ORDER BY clause is as follows:

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

• column1, column2, ...: The columns you want to retrieve.
• table_name: The name of the table.
• ORDER BY: Specifies the sorting order.
• column1, column2, ...: The columns by which the result set should be sorted.
• ASC: Ascending order (default).
• DESC: Descending order.

4.3.2 Example Queries

Consider a table named employees with the following data:

emp_id	emp_name	emp_salary
1	Alice	50000
2	Bob	60000
3	Charlie	45000
4	David	70000

Example 1: Sorting in Ascending Order

SELECT emp_id, emp_name, emp_salary
FROM employees
ORDER BY emp_salary ASC;

emp_id	emp_name	emp_salary
3	Charlie	45000
1	Alice	50000
2	Bob	60000
4	David	70000

Example 2: Sorting in Descending Order

SELECT emp_id, emp_name, emp_salary
FROM employees
ORDER BY emp_salary DESC;

emp_id	emp_name	emp_salary
4	David	70000
2	Bob	60000
1	Alice	50000
3	Charlie	45000

4.3.3 Sorting by Multiple Columns

You can also sort the result set by multiple columns. Consider a table named sales:

product_id	salesperson	sale_amount
1	Alice	200
2	Bob	150
1	Charlie	180
2	Alice	220

Example 3: Sorting by Multiple Columns

SELECT product_id, salesperson, sale_amount
FROM sales
ORDER BY product_id, sale_amount DESC;

product_id	salesperson	sale_amount
1	Charlie	180
1	Alice	200
2	Alice	220
2	Bob	150

In this example, the result set is first sorted by product_id in ascending order and then by sale_amount in descending order.

The ORDER BY clause is a powerful tool for organizing and presenting data in a way that best suits your needs. Experiment with different columns and sorting orders to refine your queries.