SQL ORDER BY clause

Posted by : Glen Sajori Sabtu, 27 September 2014

Description

The SQL ORDER BY clause is used to sort the records in the result set for a SELECT statement.

Syntax

The syntax for the SQL ORDER BY clause is:

SELECT expressions
FROM tables
WHERE conditions
ORDER BY expression [ ASC | DESC ];

Parameters or Arguments

expressions are the columns or calculations that you wish to retrieve.

tables are the tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause.

conditions are conditions that must be met for the records to be selected.

ASC is optional. It sorts the result set in ascending order by expression (default, if no modifier is provider).

DESC is optional. It sorts the result set in descending order by expression.

Note

If the ASC or DESC modifier is not provided in the ORDER BY clause, the results will be sorted by expression in ascending order (which is equivalent to "ORDER BY expression ASC").

Example - Sorting without using ASC/DESC attribute

The SQL ORDER BY clause can be used without specifying the ASC or DESC value. When this attribute is omitted from the SQL ORDER BY clause, the sort order is defaulted to ASC or ascending order.

For example:

SELECT supplier_city
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY supplier_city;

This SQL ORDER BY example would return all records sorted by the supplier_city field in ascending order and would be equivalent to the following SQL ORDER BY clause:

SELECT supplier_city
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY supplier_city ASC;

Most programmers omit the ASC attribute if sorting in ascending order.

Example - Sorting in descending order

When sorting your result set in descending order, you use the DESC attribute in your ORDER BY clause as follows:

SELECT supplier_city
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY supplier_city DESC;

This SQL ORDER BY example would return all records sorted by the supplier_city field in descending order.

Example - Sorting by relative position

You can also use the SQL ORDER BY clause to sort by relative position in the result set, where the first field in the result set is 1. The next field is 2, and so on.
For example:

SELECT supplier_city
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY 1 DESC;

This SQL ORDER BY would return all records sorted by the supplier_city field in descending order, since the supplier_city field is in position #1 in the result set and would be equivalent to the following SQL ORDER BY clause:

SELECT supplier_city
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY supplier_city DESC;

Example - Using both ASC and DESC attributes

When sorting your result set using the SQL ORDER BY clause, you can use the ASC and DESC attributes in a single SQL SELECT statement.
For example:

SELECT supplier_city, supplier_state
FROM suppliers
WHERE supplier_name = 'IBM'
ORDER BY supplier_city DESC, supplier_state ASC;

This SQL ORDER BY would return all records sorted by the supplier_city field in descending order, with a secondary sort by supplier_state in ascending order.

Source : techonthenet.com