While循环中的While循环

Question

我对这段代码有一个问题，因为第二个while循环只在第一次运行代码时运行，然后它也使得$row‘’id‘不能获得值。你能帮我找出哪里出错了吗？

$result = mysqli_query($con,"SELECT * FROM faq ORDER BY `order`");
$result2 = mysqli_query($con,"SELECT * FROM sections ORDER BY `order`");

while($row = mysqli_fetch_array($result))
  {
  echo  '<form action="../../includes/faqupdate.php" method="post" style="margin:40px;">';
  echo  '<input type="text" name="order" style="width:20px;text-align:center;" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['order'] . '\':this.value;" value="' . $row['order'] . '">';
  echo  '<input type="text" name="heading" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['heading'] . '\':this.value;" value="' . $row['heading'] . '">';
  echo  '<select name="section">';
  $section = $row['section'];
  while($row = mysqli_fetch_array($result2)) {
      $sectionname = $row['sectionname'];
      if ($sectionname == $section) {
        echo    '<option value="' . $sectionname . '" selected="selected">' . $sectionname . '</option>';
      } else {
            echo    '<option value="' . $sectionname . '">' . $sectionname . '</option>';
      }
  }
  echo      '</select>';
  echo      '<input type="text" name="id" style="width:20px;background-color:#CCC;text-align:center;" value="' . $row['id'] . '" readonly>';
  echo      '<textarea name="content" cols="98" rows="10">' . $row['content'] . '</textarea>';
  echo      '<input type="submit" name="submission" value="Update">';
  echo      '<input type="submit" name="submission" value="Delete">';
  echo  '</form>';
  }

Answer 1

我在您的代码中看到的另一个问题是您只能获取一次查询的结果集。所以要提前获取这些值，并将它们存储在一个变量中，如下所示。

$result2 = mysqli_query($con, "SELECT * FROM sections ORDER BY `order`");
$sectionnames = array();
while($row = mysqli_fetch_array($result2)) {
    $sectionnames[] = $row['sectionname'];
}


$result = mysqli_query($con,"SELECT * FROM faq ORDER BY `order`");
while($row = mysqli_fetch_array($result))
  {
  echo  '<form action="../../includes/faqupdate.php" method="post" style="margin:40px;">';
  echo  '<input type="text" name="order" style="width:20px;text-align:center;" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['order'] . '\':this.value;" value="' . $row['order'] . '">';
  echo  '<input type="text" name="heading" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['heading'] . '\':this.value;" value="' . $row['heading'] . '">';
  echo  '<select name="section">';
  $section = $row['section'];
  foreach ($sectionnames as $sectionname) {
    if ($sectionname == $section) {
        echo    '<option value="' . $sectionname . '" selected="selected">' . $sectionname . '</option>';
    } else {
        echo    '<option value="' . $sectionname . '">' . $sectionname . '</option>';
    }
  }
  echo      '</select>';
  echo      '<input type="text" name="id" style="width:20px;background-color:#CCC;text-align:center;" value="' . $row['id'] . '" readonly>';
  echo      '<textarea name="content" cols="98" rows="10">' . $row['content'] . '</textarea>';
  echo      '<input type="submit" name="submission" value="Update">';
  echo      '<input type="submit" name="submission" value="Delete">';
  echo  '</form>';
  }

Answer 2

这是因为您正在重新声明$row，请尝试：

$result = mysqli_query($con,"SELECT * FROM faq ORDER BY `order`");
$result2 = mysqli_query($con,"SELECT * FROM sections ORDER BY `order`");

while($row = mysqli_fetch_array($result))
  {
  echo  '<form action="../../includes/faqupdate.php" method="post" style="margin:40px;">';
  echo  '<input type="text" name="order" style="width:20px;text-align:center;" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['order'] . '\':this.value;" value="' . $row['order'] . '">';
  echo  '<input type="text" name="heading" onclick="this.value=\'\';" onfocus="this.select()" onblur="this.value=!this.value?\'' . $row['heading'] . '\':this.value;" value="' . $row['heading'] . '">';
  echo  '<select name="section">';
  $section = $row['section'];
  while($row2 = mysqli_fetch_array($result2)) {
      $sectionname = $row2['sectionname'];
      if ($sectionname == $section) {
        echo    '<option value="' . $sectionname . '" selected="selected">' . $sectionname . '</option>';
      } else {
            echo    '<option value="' . $sectionname . '">' . $sectionname . '</option>';
      }
  }
  echo      '</select>';
  echo      '<input type="text" name="id" style="width:20px;background-color:#CCC;text-align:center;" value="' . $row['id'] . '" readonly>';
  echo      '<textarea name="content" cols="98" rows="10">' . $row['content'] . '</textarea>';
  echo      '<input type="submit" name="submission" value="Update">';
  echo      '<input type="submit" name="submission" value="Delete">';
  echo  '</form>';
  }

Answer 3

在$row2的第二个while条件中重命名$row