这是代码

Question

我正在创建3个下拉列表，它基于彼此的选择，所以第一个选择i正常但第二个依赖于第一个选择而第三个依赖于第二个选择这就是表结构就像

类别子类别和子子类别

这是代码

<?php

require "config.php"; //  Database details 
?>

<!doctype html public "-//w3c//dtd html 3.2//en">

<html>

<head>
<title>Demo of Three Multiple drop down list box from plus2net</title>
<meta name="GENERATOR" content="Arachnophilia 4.0">
<meta name="FORMATTER" content="Arachnophilia 4.0">
<SCRIPT language=JavaScript>
function reload(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
self.location='dd3.php?cat=' + val ;
}
function reload3(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
var val2=form.subcat.options[form.subcat.options.selectedIndex].value; 

self.location='dd3.php?cat=' + val + '&cat3=' + val2 ;
}

</script>
</head>

<body>
<?



$quer2=mysql_query("SELECT DISTINCT category,cat_id FROM category order by category"); 

$cat=$_GET['cat']; 
if(isset($cat) and strlen($cat) > 0){
$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory where cat_id=$cat order by subcategory"); 
}else{$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory order by subcategory"); } 




$cat3=$_GET['cat3'];
if(isset($cat3) and strlen($cat3) > 0){
$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 where subcat_id=$cat3 order by subcat2"); 
}else{$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 order by subcat2"); } 


echo "<form method=post name=f1 action='dd3ck.php'>";

echo "<select name='cat' onchange=\"reload(this.form)\"><option value=''>Select one</option>";
while($noticia2 = mysql_fetch_array($quer2)) { 
if($noticia2['cat_id']==@$cat){echo "<option selected value='$noticia2[cat_id]'>$noticia2[category]</option>"."<BR>";}
else{echo  "<option value='$noticia2[cat_id]'>$noticia2[category]</option>";}
}
echo "</select>";

echo "<select name='subcat' onchange=\"reload3(this.form)\"><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer)) { 
if($noticia['subcat_id']==@$cat3){echo "<option selected value='$noticia[subcat_id]'>$noticia[subcategory]</option>"."<BR>";}
else{echo  "<option value='$noticia[subcat_id]'>$noticia[subcategory]</option>";}
}
echo "</select>";

echo "<select name='subcat3' ><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer3)) { 
echo  "<option value='$noticia[subcat2]'>$noticia[subcat2]</option>";
}
echo "</select>";



echo "<input type=submit value='Submit the form data'></form>";
?>

</body>

</html>

谁能帮助我？

，这是我运行此代码时的输出

0){ $quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory where cat_id=$cat order by subcategory"); }else{$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory order by subcategory"); } $cat3=$_GET['cat3']; if(isset($cat3) and strlen($cat3) > 0){ $quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 where subcat_id=$cat3 order by subcat2"); }else{$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 order by subcat2"); } echo "
"; echo ""; echo ""; echo ""; echo "
"; ?>

Answer 1

在较低的PHP代码开头只有<?而不是<?php，＆gt;从if语句结束我认为。但这可能不是问题所在。

Answer 2

可能是您的服务器中已禁用PHP短标记。因此，如果您使用PHP的短标签，它将无法正常工作。

检查此链接以了解如何在PHP中启用短标签。 http://www.tomjepson.co.uk/enabling-short-tags-in-php/

但是如果你不能启用短标签，那么你需要正确打开PHP标签

<?错误应该是<?php。在代码中更改它。完整的代码将是：

<?php

require "config.php"; //  Database details 
?>

<!doctype html public "-//w3c//dtd html 3.2//en">

<html>

<head>
<title>Demo of Three Multiple drop down list box from plus2net</title>
<meta name="GENERATOR" content="Arachnophilia 4.0">
<meta name="FORMATTER" content="Arachnophilia 4.0">
<SCRIPT language=JavaScript>
function reload(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
self.location='dd3.php?cat=' + val ;
}
function reload3(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
var val2=form.subcat.options[form.subcat.options.selectedIndex].value; 

self.location='dd3.php?cat=' + val + '&cat3=' + val2 ;
}

</script>
</head>

<body>
<?php



$quer2=mysql_query("SELECT DISTINCT category,cat_id FROM category order by category"); 

$cat=$_GET['cat']; 
if(isset($cat) and strlen($cat) > 0){
$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory where cat_id=$cat order by subcategory"); 
}else{$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory order by subcategory"); } 




$cat3=$_GET['cat3'];
if(isset($cat3) and strlen($cat3) > 0){
$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 where subcat_id=$cat3 order by subcat2"); 
}else{$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 order by subcat2"); } 


echo "<form method=post name=f1 action='dd3ck.php'>";

echo "<select name='cat' onchange=\"reload(this.form)\"><option value=''>Select one</option>";
while($noticia2 = mysql_fetch_array($quer2)) { 
if($noticia2['cat_id']==@$cat){echo "<option selected value='$noticia2[cat_id]'>$noticia2[category]</option>"."<BR>";}
else{echo  "<option value='$noticia2[cat_id]'>$noticia2[category]</option>";}
}
echo "</select>";

echo "<select name='subcat' onchange=\"reload3(this.form)\"><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer)) { 
if($noticia['subcat_id']==@$cat3){echo "<option selected value='$noticia[subcat_id]'>$noticia[subcategory]</option>"."<BR>";}
else{echo  "<option value='$noticia[subcat_id]'>$noticia[subcategory]</option>";}
}
echo "</select>";

echo "<select name='subcat3' ><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer3)) { 
echo  "<option value='$noticia[subcat2]'>$noticia[subcat2]</option>";
}
echo "</select>";



echo "<input type=submit value='Submit the form data'></form>";
?>

</body>

</html>

php mysql填充了几个动态下拉列表

这是代码

，这是我运行此代码时的输出

2 个答案: