php 三级联动菜单

数据库结构

-- 表的结构 `bigclass`
--
create table `bigclass` (
`bigclassid` int(11) not null auto_increment,
`bigclassname` varchar(200) collate utf8_unicode_ci not null,
`sort` int(11) not null,
`suoshu` int(1) not null,
primary key (`bigclassid`)
) engine=myisam default charset=utf8 collate=utf8_unicode_ci auto_increment=19 ;
-- 表的结构 `smallclass`
--
create table `smallclass` (
`smallclassid` int(11) not null auto_increment,
`smallclassname` varchar(200) collate utf8_unicode_ci not null,
`bigclassid` int(11) not null,
`sort` int(11) not null,
primary key (`smallclassid`)
) engine=myisam default charset=utf8 collate=utf8_unicode_ci auto_increment=7 ;
-- 表的结构 `minclass`
--
create table `minclass` (
`minclassid` int(10) not null auto_increment,
`minclassname` varchar(200) not null,
`bigclassid` int(10) not null,
`smallclassid` int(10) not null,
`sort` int(10) not null,
primary key (`minclassid`)
) engine=myisam default charset=latin1 auto_increment=3 ;

代码如下

<script language = "javascript">
var onecount;
onecount=0;
subcat = new array();
<?
//类别选择
mysql_select_db($database_lr, $lr);
$sql = "select * from smallclass order by sort";
$result = mysql_query( $sql );
$count = 0;
while($res = mysql_fetch_row($result)){
?>
subcat[<?=$count?>] = new array("<?=$res[1]?>","<?=$res[4]?>","<?=$res[0]?>");
<?
$count++;
}
?>
onecount=<?php echo $count?>
//联动函数
function changelocation(bigclassid)
{
document.myform.smallclassid.length = 0;
var bigclassid=bigclassid;
var i;
document.myform.smallclassid.options[0] = new option('请选择二级分类','');
for (i=0;i < onecount; i++)
{
if (subcat[i][1] == bigclassid)
{
document.myform.smallclassid.options[document.myform.smallclassid.length] = new option(subcat[i][0], subcat[i][2]);
}
}
}
</script>
<?php
mysql_select_db($database_lr, $lr);
$sql2 = "select * from minclass order by sort";
$result2 = mysql_query( $sql2 );
$count2 = 0;
?>
<script language = "javascript">
//如果这个数组中含有双引号则不能使用。即二级和三级类不能含有双引号
var onecount2;
onecount2=0;
subcat2 = new array();
<?php
$count2 = 0;
while($res2 = mysql_fetch_row($result2)){
?>
subcat2[<?php echo $count2?>] = new array("<?php echo $res2[1]?>","<?php echo $res2[3]?>","<?php echo $res2[0]?>");
<?php
$count2++;
}
?>
onecount2=<?php echo $count2?>;
function changelocation2(smallclassid)
{
document.myform.minclassid.length = 0;
var smallclassid=smallclassid;
var j;
document.myform.minclassid.options[0] = new option('请选择三级分类','');
for (j=0;j < onecount2; j++)
{
if (subcat2[j][1] == smallclassid)
{
document.myform.minclassid.options[document.myform.minclassid.length] = new option(subcat2[j][0], subcat2[j][2]);
}
}
}
</script>
<select name="bigclassid" onchange="changelocation(document.myform.bigclassid.options[document.myform.bigclassid.selectedindex].value)" size="1">
<option selected value="">请指定一级分类</option>
<?
$sql = "select * from bigclass order by sort";
$result = mysql_query( $sql );
while($res = mysql_fetch_row($result)){
?>
<option value="<? echo $res[0]; ?>"><? echo $res[1]?></option>
<? } ?>
</select>
<select name="smallclassid" onchange="changelocation2(document.myform.smallclassid.options[document.myform.smallclassid.selectedindex].value)" size="1">
<option selected value="">请指定二级分类</option>
</select>
<select name="minclassid" size="1">
<option selected value="">==所有三级分类==</option>
</select>