PHP & MySQL - Sorting Data

The MySQL ORDER BY clause is used to sort the result table in ascending or descending order. By default, ORDER BY clause sorts the result in ascending order, however it can be specified using ASC keyword. To sort the result in descending order, DESC keyword is used.

The syntax for using ORDER BY keyword is given below:

SELECT column1, column2, column3, ...
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;

Along with this, to connect to the MySQL server, mysqli_connect() function can be used. After establishing the connection, mysqli_query() function can be used to perform a query on the database.

The num_rows() function can be used to check if there are more than zero rows returned. Then, the fetch_assoc() function can be used to fetch the result set as an associative array. Later on the free_result() function can be used to free the memory associated with the result.

Sorting Data - Object-oriented style

Consider a database containing a table called Employee with the following records:

EmpID	Name	City	Age	Salary
1	John	London	25	3000
2	Marry	New York	24	2750
3	Jo	Paris	27	2800
4	Kim	Amsterdam	30	3100
5	Ramesh	New Delhi	28	3000
6	Huang	Beijing	28	2800

The example below demonstrates how to use the ORDER BY clause to sort the data of this table by Salary using object-oriented style.

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDatabase";

//establishing connection 
$mysqli = new mysqli($servername, $username, $password, $dbname);

//checking connection
if ($mysqli->connect_errno) {
  echo "Failed to connect to MySQL: ". $mysqli->connect_error;
  exit();
}

//getting query result from the database
$sql = "SELECT Name, Age, Salary 
FROM Employee 
ORDER BY Salary ASC";
$result = $mysqli->query($sql);

//fetching associative array
while ($row = $result->fetch_assoc()) {
  printf("%s, %d, %d\n", $row["Name"], $row["Age"], $row["Salary"]);
}

//free result set
$result->free_result();

//closing the connection
$mysqli->close();
?>

The output of the above code will be:

Marry, 24, 2750
Jo, 27, 2800
Huang, 28, 2800
John, 25, 3000
Ramesh, 28, 3000
Kim, 30, 3100

Sorting Data - Procedural style

To obtain the same result using procedural style, the following script can be used.

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDatabase";

//establishing connection 
$mysqli = mysqli_connect($servername, $username, $password, $dbname);

//checking connection
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: ". mysqli_connect_error();
  exit();
}

//getting query result from the database
$sql = "SELECT Name, Age, Salary
FROM Employee 
ORDER BY Salary ASC";
$result = mysqli_query($mysqli, $sql);

//fetching associative array
while ($row = mysqli_fetch_assoc($result)) {
  printf("%s, %d, %d\n", $row["Name"], $row["Age"], $row["Salary"]);
}

//free result set
mysqli_free_result($result);

//closing the connection
mysqli_close($mysqli);
?>

The output of the above code will be:

Marry, 24, 2750
Jo, 27, 2800
Huang, 28, 2800
John, 25, 3000
Ramesh, 28, 3000
Kim, 30, 3100

Complete PHP MySQLi Reference

For a complete reference of all properties, methods and functions of PHP MySQLi extension, see PHP MySQLi Reference.