在将数据插入书籍表时选择类别和子类别答案

【问题标题】：Selecting categories and subcategories at inserting data into books table在将数据插入书籍表时选择类别和子类别
【发布时间】：2014-01-10 02:59:56
【问题描述】：

我在书店网站上有三张桌子。类别、子类别和书籍我想在将数据插入书籍表时选择类别和相关子类别，但子类别无法从类别中获取 id 并且未在列表中显示任何子类别我的代码如下：

<th scope="col">Select Category</th>
<th scope="col"><select name="cat">
<?php
include("config.php");
$catsql = "SELECT * FROM categories;";
$catres = mysql_query($catsql);
while($catrow= mysql_fetch_assoc($catres)) {
echo "<option value='" . $catrow['id']
. "'>" . $catrow['cat'] . "</option>";
}
?>

</select></th>
</tr>
<tr>
<th scope="col">Select Subcategory
</th>
<th scope="col"><select name="subcat">
<?php
$cat=$catrow['id'];
$subsql="select * from subcat where catid=$cat;";
$subrs=mysql_query($subsql);
while($subrow=mysql_fetch_array($subrs)){
echo "<option value='" . $subrow['id']
. "'>" . $subrow['subcat'] . "</option>";

}
?>
</select>
</th>

【问题讨论】：

标签： php mysql select

【解决方案1】：

当用户选择任何类别来填充子类别下拉列表时，您应该使用 Ajax 调用。

【讨论】：

【解决方案2】：

我已经使用 java 脚本完成了这项工作：

    <?php
    $db = new mysqli('localhost','root','','sha');
    $query = "SELECT * FROM categories;";
    $result = $db->query($query);

  while($row = $result->fetch_assoc()){
    $categories[] = array("id" => $row['id'], "val" => $row['cat']);
  }

  $query = "SELECT id, catid, subcat FROM subcat";
  $result = $db->query($query);

  while($row = $result->fetch_assoc()){
    $subcats[$row['catid']][] = array("id" => $row['id'], "val" => $row['subcat']);
  }

  $jsonCats = json_encode($categories);
  $jsonSubCats = json_encode($subcats);


?>

<!docytpe html>
<html>

  <head>
    <script type='text/javascript'>
      <?php
        echo "var categories = $jsonCats; \n";
        echo "var subcats = $jsonSubCats; \n";
      ?>
      function loadCategories(){
        var select = document.getElementById("categoriesSelect");
        select.onchange = updateSubCats;
        for(var i = 0; i < categories.length; i++){
          select.options[i] = new Option(categories[i].val,categories[i].id);          
        }
      }
      function updateSubCats(){
        var catSelect = this;
        var catid = this.value;
        var subcatSelect = document.getElementById("subcatsSelect");
        subcatSelect.options.length = 0; //delete all options if any present
        for(var i = 0; i < subcats[catid].length; i++){
          subcatSelect.options[i] = new Option(subcats[catid][i].val,subcats[catid][i].id);
        }
      }
    </script>

  </head>

  <body onload='loadCategories()'>
  <form action="storebooks.php" method="post"><table><tr><th scope="col">Select Category</th>
    <th scope="col"><select id='categoriesSelect' <select name="cid">
    </select></th>
  </tr>
<tr>
    <th scope="col">Select Subcategory
    </th>
    <th scope="col">
    <select id='subcatsSelect' name="subcatid">
    </select></th>
  </tr>
  <tr>
    <th scope="col"><p>Title</p></th>
    <th scope="col"><input name="title" type="text" /></th>
  </tr>
  <tr>
    <th scope="col">Author</td>
    <th scope="col"><input type="text" name="author" id="author" /></td>
  </tr>
  <tr>
    <td>description</td>
    <td><textarea name="bookdesc" cols="30" rows="15"></textarea></td>
  </tr>
  <tr>
    <th scope="col"><p>keywords</p></th>
    <th scope="col"><input name="keywords" type="text" /></th>
  </tr>
   <tr>
    <th scope="col"><p>Image</p></th>
    <th scope="col"><input name="image" type="text" /></th>
  </tr>
  <tr>
    <th scope="col"><p>Order</p></th>
    <th scope="col"><input name="order" type="text" /></th>
  </tr>
    <tr>
    <td></td>
    <td><input name="submit" type="submit" value="submit" id="submit" /></td>
  </tr>
</table>
</form>

</body>
</html>

【讨论】：