How to Calculate a User\'s Age from Their Date of Birth?

Calculating Age from Date of Birth

To calculate a user's age based on their date of birth stored in an SQL database, you can leverage various methods.

PHP Calculation:

If you have the user's birthdate as a string in PHP, you can utilize the following functions:

<code class="php"><?php
$birthdate = '1999-03-15';

// PHP >= 5.3.0: Object-oriented approach
$from = new DateTime('1970-02-01');
$to   = new DateTime($birthdate);
$age = $from->diff($to)->y;

// PHP >= 5.3.0: Procedural approach
$age = date_diff(date_create('1970-02-01'), date_create($birthdate))->y;

echo $age; // Output: 14
?></code>

MySQL Calculation:

In MySQL, you can calculate the age directly using the TIMESTAMPDIFF() function:

<code class="sql">SELECT TIMESTAMPDIFF(YEAR, '1999-03-15', CURDATE()) AS age;</code>

This query will return the age of the user based on the provided birthdate.

Example Integration:

To integrate this calculation into your existing code, you can modify the SQL query to retrieve the user's birthdate, then use the above methods to calculate their age before outputting it.

<code class="php"><?php
$id = intval($_GET['id']);
$dn = mysql_fetch_array($dn);
$dn = mysql_query('select username, email, skype, avatar,
                    date, signup_date, gender from users where id="'.$id.'"');
$dnn = mysql_fetch_array($dn);

$age = // Calculate age using any of the methods above

echo "Username: {$dnn['username']}, Age: {$age}";
?></code>

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