在将数据插入书籍表时选择类别和子类别
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【中文标题】在将数据插入书籍表时选择类别和子类别【英文标题】：Selecting categories and subcategories at inserting data into books table 【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】：
【参考方案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】：
【参考方案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】：
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