PHP& MySQL用户名提交问题 [英] PHP & MySQL username submit problem

问题描述

我想允许用户随时在其中的用户名字段为空，但收到用户名错误消息Your username is unavailable!如何解决此问题?

I want to allow users to either have there username field empty at any time but I get the username error message Your username is unavailable! how can I correct this problem?

这是PHP代码.

if(isset($_POST['username'])) {

    $u = "SELECT * 
          FROM users 
          WHERE username  = '$username'
          AND user_id <> '$user_id'";
    $r = mysqli_query ($mysqli, $u) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($mysqli));

    if (mysqli_num_rows($r) == TRUE) { // Unavailable.
        echo '<p class="error">Your username is unavailable!</p>';
        $username = NULL;
    } else if(mysqli_num_rows($r) == 0) { // Available.
        $username = mysqli_real_escape_string($mysqli, $purifier->purify(htmlentities(strip_tags($_POST['username']))));
    }
}

这些示例均无效.我想知道如何让我的用户没有用户名?

推荐答案

if(isset($_POST['username']) && trim($_POST['username'])!=='') {

否则，即使提交的表单具有空字段，也会设置$ _POST ['username'].

Otherwise, $_POST['username'] will be set even if the form is submitted with an empty field.

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