ORDER BY Clause in SQL

The ORDER BY clause is used to sort the result set of a SQL query based on one or more columns. You can sort in ascending or descending order.

Syntax:

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

• ASC = Ascending order (smallest to largest, A to Z). This is the default.

• DESC = Descending order (largest to smallest, Z to A).

Example:

Retrieve all employees sorted by their salary from highest to lowest:

SELECT employee_name, salaryFROM employeesORDER BY salary DESC;

Example with multiple columns:

Sort employees by department ascending, then by salary descending within each department:

SELECT employee_name, department_id, salaryFROM employeesORDER BY department_id ASC, salary DESC;

Important Points:

• The ORDER BY clause comes after the WHERE and GROUP BY clauses (if used).

• If you omit ASC or DESC, ASC is assumed by default.

• You can order by column name, alias, or column position (e.g., ORDER BY 1 orders by the first selected column).

• Sorting on text columns is usually case-insensitive, but this depends on the database collation settings.

If you want, I can provide examples on how ORDER BY works with NULL values or how it affects query performance.