如何在输入字段中使用选择选项的当前值答案

【问题标题】：how to use the current value of a select option inside input field如何在输入字段中使用选择选项的当前值
【发布时间】：2015-10-21 18:26:03
【问题描述】：

我在 Xampp 中使用 phpmyadmin，我在其中创建了两个表；表 1：具有 cat_id 和 cat_name 属性的类别（其中 cat_id 是主键）表 2：具有 item_id、item_name、item_price ... cat_id 属性的项目（其中 item_id 是主键，cat_id 是外键）我也在phpmyadmin中建立了正确的关系。问题是在 php.ini 中的选择标记中使用值，即所选 cat_name 的 cat_id。附言。我知道自己是 SQL 注入的对象。

PHP

<?php  
require ('config.php'); 
if(isset($_POST['check']))
{
if(isset($_POST['button'])) 
{
$catname = $_POST['cat'];

$que1 = "SELECT * FROM category WHERE cat_name = '$catname'";
$res1 = mysql_query($que1);
$row = mysql_fetch_array($res1);
$cat_db = $row['cat_name'];

if($catname == $cat_db || $catname == "")
{   
    echo "Catergory: $catname already exits. Failed to be inserted.";
}
else
{
    $que = "INSERT INTO category (cat_name) VALUES('$catname')";
    $res = mysql_query($que);
    echo "Catergory: $catname inserted successfully.";

}
die();
}


  if(isset($_POST['item_name']))
  {
      $i_id = $_POST['item_id'];
      $i_name = $_POST['item_name'];
      $i_quan = $_POST['item_quantity'];
      $i_size = $_POST['item_size'];
      $i_price = $_POST['item_price'];
      $cat_id = $_POST['cat_id'];

$que = "INSERT INTO item(item_name, item_quantity, item_size, item_price, cat_id) VALUES('$i_name','$i_quan','$i_size','$i_price', '$cat_id')";
$run = mysql_query($que);
if(!$run)
   echo "Item Details failed to Update.";       
  }
}
?>

HTML

<!DOCTYPE html>
<html>
<head>
<link rel = "stylesheet" href = "login.css">
</head>
<body>
<form action = "" method = "POST">

<p><label class = "field">Add Category:</label></p>
<input type = "text" name = "cat" class = "textbox-300" pattern = "[a-zA-Z0-9\. ]+"  title = "Please enter your Category Name">
<button type=  "submit" onclick = "location.href = '';" id = "savebutton" name = "button">Add Now</button>
<p><label class = "field">Add Item:</label></p>


<select name="cate">
<?php 
$que1 = "SELECT * FROM category";
$res1 = mysql_query($que1);
while($row = mysql_fetch_array($res1))
{    
$cat_id_db = $row['cat_id'];                 //use array over here
$cat_db = $row['cat_name'];                  //use array over here
?>

<option value="<?php echo $cat_id_db; ?>" ><?php echo $cat_db;?></option>

<?php } ?>
</select>


<?php 
$que1 = "SELECT * FROM category WHERE cat_name = '$cat_db'";      //yahan masla hai bhai, how do i set '$cat_db' into a static variable?
$res1 = mysql_query($que1);
$row = mysql_fetch_array($res1);
$cat_db_id = $row['cat_id'];
?>

<p><label class = "field">Category ID:</label></p>
<input type = "text" name = "cat_id" value = "<?php echo $cat_id_db; ?>" class = "textbox-300" pattern = "[a-zA-Z0-9\. ]+"> <!-- this is the PROBLEM how do i use the value of a selected option ONLY? -->
 <p><label class = "field">Item ID:</label></p>
 <input type = "text" name = "item_id" class = "textbox-300" pattern = "[a-zA-Z0-9\. ]+"title = "Please enter your Item ID">
 <p><label class = "field">Item Name:</label></p>
 <input type = "text" name = "item_name" class = "textbox-300" pattern = "[a-zA-Z ]+"title = "Please enter your Item Name">
 <p><label class = "field">Item Quantity:</label></p>
 <input type = "text" name = "item_quantity" class = "textbox-300" pattern = "[a-zA-Z0-9\. ]+"title = "Please enter your Item Quantity">
 <p><label class = "field">Item Size:</label></p>
 <input type = "text" name = "item_size" class = "textbox-300" pattern = "[a-zA-Z0-9\.\, ]+"title = "Please enter your Item Size">
 <p><label class = "field">Item Price:</label></p>
 <input type = "text" name = "item_price" class = "textbox-300" pattern = "[a-zA-Z0-9\.\, ]+"title = "Please enter your Item Price">


 <input type = "hidden" name = "check">
 <input type = "submit" class = "button" name = "sub"  value = "Save">

 </form> 
 </body>
 </html>

【问题讨论】：

我很难理解这个问题，起初我以为是因为您的select 的名称为cate，但您在php 中寻找cat 但后来意识到您有一个名为 cat 的 text 字段。如果您在问题中缩小代码以便仅存在相关代码而不是整个 html 页面和 php 脚本，则更容易回答。
@martincarlin87，对不起。我已经评论了我遇到问题的行。请查看
Category ID:
标签下方。

标签： php mysql html select phpmyadmin

【解决方案1】：

您将拥有所选子猫的 ID。所以写一个查询来获取 cat_id。

select * from sub_category where item_id = "posted id" 你会得到主分类id。

【讨论】：

您的意思是在查询中使用选定的选项吗？就像是; SELECT * FROM 类别 WHERE cat_name = ' ? ';我写什么代替'？ -.-

【解决方案2】：

感谢这里的一位成员，我找到了答案，所以我把它贴在这里，以防有人来这里寻找同样的东西。

<select name="cate" onchange="changeInput(this.value);">
    <?php //your php code here ?>
</select>

<p><label class = "field">Category ID:</label></p>
<input type = "text" name = "cat_id" id="cat_id" value = "change select to see me change" class = "textbox-300" pattern = "[a-zA-Z0-9\. ]+"  title = "Please enter your Item Price">
</form>

<script>
var changeInput = function (val){
    var input = document.getElementById("cat_id");
    input.value = val;
}
</script>

【讨论】：