SQL Overview: Data Sequencing with ORDER BY

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In SQL, the ORDER BY clause is used to sort the result set of a query based on one or more columns. It is commonly used with the SELECT statement, but it can also be used with other SQL statements such as UPDATE, DELETE, and MERGE when ordering is relevant.

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 in the result set.
• table_name: The name of the table from which to retrieve data.
• ORDER BY: Specifies the sorting order.
• column1 [ASC|DESC], column2 [ASC|DESC], ...: The columns by which you want to sort the result set. ASC stands for ascending order (default), and DESC stands for descending order.

1. Sorting in Ascending Order:

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

This query retrieves the first and last names from the employees table and sorts the result set first by last_name in ascending order and then by first_name in ascending order.

2. Sorting in Descending Order: