Question

我在声明中的输出出现问题。我正在尝试为以dB为单位的用户名的每个实例加1。我有以下代码：

$username = strtolower($fname . "_" . $lname);

$check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
$check_username_query->bind_param('s', $username);
$check_username_query->execute();

$result = $check_username_query->get_result();
$num_rows = $result->num_rows;  //count number of rows in the result

$i = 0;

//if username exists add number to username
while ($num_rows != 0) {

    $i++; //Add 1 to i
    $username = $username . "_" . $i;

    $check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
    $check_username_query->bind_param('s', $username);
    $check_username_query->execute();

    $result = $check_username_query->get_result();
    $num_rows = $result->num_rows;
}

这对于前两个工作正常：例如。 $fname是约翰，$lname是史密斯。我得到$username为john_smith。对于下一个，我得到john_smith_1但对于下一个，我得到john_smith_1_2，而在之后的我得到john_smith_1_2_3，依此类推。我想要的第三种实例是john_smith_3，john_smith_4等。

$i中的$username = $username . "_" . $i;会继续增加吗？

Answer 1

使用这段代码：

$username = strtolower($fname . "_" . $lname);

$check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
$check_username_query->bind_param('s', $username);
$check_username_query->execute();

$result = $check_username_query->get_result();
$num_rows = $result->num_rows;  //count number of rows in the result

$i = 0;

//if username exists add number to username
while ($num_rows != 0) {

    $i++; //Add 1 to i
    $new_username = $username . "_" . $i;

    $check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
    $check_username_query->bind_param('s', $new_username );
    $check_username_query->execute();

    $result = $check_username_query->get_result();
    $num_rows = $result->num_rows;
}

Answer 2

我最终这样做：

$username = strtolower($fname . "_" . $lname);

$check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
$check_username_query->bind_param('s', $username);
$check_username_query->execute();

$result = $check_username_query->get_result();
$num_rows = $result->num_rows;  //count number of rows in the result

$new_username = 1;

$i = 0;
//if username exists add number to username
while ($num_rows != 0) {

    $i++; //Add 1 to i
    $new_username = $username . "_" . $i;

    $check_username_query = mysqli_prepare($con, "SELECT username FROM users WHERE username=?");
    $check_username_query->bind_param('s', $new_username);
    $check_username_query->execute();

    $result = $check_username_query->get_result();
    $num_rows = $result->num_rows;

}

    if($new_username == 1){
      $username = $username;
    } else {
      $username = $new_username;
    }

需要将$new_username分配为某物（我选择1），然后在$num_rows == 0和while循环未参与的情况下，将其放在条件末尾。根据需要工作。感谢您的指导。

使用运算符在while循环中添加1

2 个答案: