Question

我正在尝试制作基于排名的导航系统。因此，用户的排名越高，他获得的导航选项就越多。我做了：

$rank = "SELECT rank FROM users WHERE username = '".$_SESSION['username']."'";

然后我尝试了：

if ($rank > 5) { 
// show rank 5 navigation
} else {
// show lower than rank 5 navigation
}

但它对我不起作用..

有什么想法吗？

Answer 1

以下示例应足以让您开始正确的路径。

查看PHP Prepared Statements，了解有关从MySQL中提取信息的最佳方法的详细信息。

另外，看看MySQL的Comparison Functions and Operators和PHP的比较运算符。

<?php

    // Place everything in a function to keep it somewhat organized.
    function displaySpecialUserMenu($username){

          // Connect to database
          $db = new PDO('mysql:host=localhost;dbname=testDatabaseName', 'testDatabaseUser', 'testPassword123');

          // Turn on error mode. Turn this OFF for production.
          $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

          // Select statement should return "1" if a user's rank is above 5
          $statement = $db->prepare('SELECT EXISTS(SELECT 1 FROM users WHERE rank > 5 AND username = :username');

          // Prepare the variables for the statement.
          $statement->bindParam(':username', $username, PDO::PARAM_STR);

          // Run the prepared statement
          $statement->execute();

          // Store the result (It'll be either a 0 or a 1) in $result
          $result = $statement->fetchColumn();

          if($result>0){
              // User's rank is greater than 5
              // Display menu here
              echo '[high_rank_menu_here]';
           }else{
              // User's rank is greater than 5
              // Display menu here
              echo '[low_rank_menu_here]';
           }


}

// Place this line where you want your menu to display.
displaySpecialUserMenu($_SESSION['username']);


?>

您也可以使用PHP而不是MySQL来执行逻辑，如上例所示。

<?php

function displaySpecialUserMenu($username){

        // Connect to database
        $db = new PDO('mysql:host=localhost;dbname=testDatabaseName', 'testDatabaseUser', 'testPassword123');

        // Turn on error mode. Turn this OFF for production.
        $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        // Select rank from user
        $statement = $db->prepare("SELECT rank FROM users WHERE username = :username");

        // Prepare the variables for the statement.
        $statement->bindParam(':username', $username, PDO::PARAM_STR);

        // Run the prepared statement
        $statement->execute();

        // Store the result
        $rank = $statement->fetchColumn();

        if($rank>5){
            // User's rank is greater than 5
            // Display menu here
            echo '[high_rank_menu_here]';
        }else{
              // User's rank is greater than 5
              // Display menu here
              echo '[low_rank_menu_here]';
        }
}

// Place this line where you want your menu to display.
displaySpecialUserMenu($_SESSION['username']);


?>

如果用户等级高于，则为

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