对于初学者来说，PHP语言的掌握还是需要在具体实践中不断的去积累经验来增加我们对PHP的理解程度。下面就以一个范例为大家介绍PHP二级联动菜单的实现方法。#t#

PHP二级联动菜单代码示例：

1. <scriptlanguage="JavaScript">
2. varonecount;
3. onecount=0;
4. subcat=newArray();
5. <?php
6. mysql_connect("localhost","charles",
   "charles");
7. mysql_select_db("_crm");
8. $sql="select*fromsite";
9. $result=mysql_query($sql);
10. $count=0;
11. while($res=mysql_fetch_row($result)){
12. ?>
13. subcat[<?phpecho$count?>]=newArray
    ("<?phpecho$res[0]?>","<?phpecho
    $res[2]?>","<?phpecho$res[1]?>");
14. <?php
15. $count++;
16. }
17. echo"onecount=$count;";
18. ?>
19. //联动函数
20. functionchangelocation(locationid)
21. {
22. document.myform.ctype.length=0;
23. varlocationidlocationid=locationid;
24. vari;
25. for(i=0;i<onecount;i++)
26. {
27. if(subcat[i][2]==locationid)
28. {
29. //varnewnewOption1=newOption(subcat[i]
    [1],subcat[i][0]);
30. //document.all.ctype.add(newOption1);
31. document.myform.ctype.options[document.
    myform.ctype.length]=newOption(subcat
    [i][1],subcat[i][0]);
32. }
33. }
34. }
35. </script>
36. <formmethod="post"name="myform"
    action="ru_query.php">
37. <selectname="type"onChange="changelocation(
    document.myform.type.options[document.myfo
    rm.type.selectedIndex].value)"size="1">
38. <optionselectedvalue="">main</option>
39. <?php
40. $sql="select*fromentreprise";
41. $result=mysql_query($sql);
42. while($res=mysql_fetch_row($result)){
43. ?>
44. <optionvalue="<?phpecho$res[0];?>">
45. <?phpecho$res[1];?></option>
46. <?php}?>
47. </select>
48. <selectname="ctype">
49. <optionselectedvalue="">sub</option>
50. </select>
51. <inputtype="submit"name="Submit"value="search">
52. </form>

以上代码就是PHP二级联动菜单的具体实现方法。