PHP单独如果其他声明

Question

<?php
    extract( $_GET );       
    $sql = "SELECT * FROM tablename order by Name DESC";
    $sql = "SELECT * FROM tablename where age = "31";
    $db = mysql_connect("localhost","root","password"); 
    if (!$db) {
    die("");
    }
    $db_select = mysql_select_db('databasename',$db);
    if (!$db_select) {
    die("");
    }
    if ( !( $result = mysql_query( $sql, $db ) ) ) {
    print( "Could not execute query! <br />" );
    die( mysql_error() . "</body></html>" );
    } // end if

    echo "<table>
    <tr>
    <th>Name</th>
    <th>Age</th>
    </tr>";

    while($row = mysql_fetch_array($result)){
        echo "<tr>";
        echo "<td>".$row['Name']."</td>";
        echo "<td>".$row['Age']."</td>";
    }
    echo "</table>";
    mysql_close( $db );
?>

Where should I add an if else statement for name and age that runs the sql statement when either the name or age is selected? Name and Age is from different column but in the same table

Answer 1

if(isset($_GET['age'])) {
    $sql = 'SELECT * FROM tablename where age = ' . $_GET['age'];
} else if(isset($_GET['name'])) {
    $sql = 'SELECT * FROM tablename order by Name DESC';
}

Then you could use it for URLs like:

• www.example.com?age=31
• www.example.com?name

Just note that this is a very simplified example, you need to validate the input as well.

EDIT: You should not use mysql* (deprecated) functions, use mysqli* or PDO instead. For more information about mysql* functions read answers posted on this question.