1.ajax的基础知识
ajax是结合了jquery、php等几种技术延伸出来的综合运用的技术，不是新的内容。ajax也是写在<script>标签里面的。
如果使用ajax一定是要有1个处理页面的，处理页面只是操作数据库并且返回值，页面都是ajax处理的。
2.用ajax做登录页面 denglu.php
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><script src="../jquery-1.11.2.min.js"></script><title>无标题文档</title></head><body><div>用户名：<input type="text" id="uid" /></div><div>密码：<input type="text" id="pwd" /></div><div><input type="button" value="登录" id="btn" /></div></body><script type="text/javascript"> $(document).ready(function(e) { ???$("#btn").click(function(){//给按钮加点击事件 ???????????????//取用户名和密码 var u = $("#uid").val();//取输入的用户名 var p = $("#pwd").val();//取输入的密码 ???????????????//调ajax $.ajax({ ???????????????????????url:"dengluchuli.php", data:{u:u,p:p},//第二个u和p只是变量，可以随意写，dengluchuli.php里面的u和p都是第一个。 type:"POST", dataType:"TEXT", success: function(data){ if(data.trim()=="OK")//要加上去空格，防止内容里面有空格引起错误。 ?{ ???????????????????????window.location.href="main.php";//js跳转页面，要记住。 ?} else { echo("用户名或密码错误"); ???????????????????} ???????????????????????????} ???????????????????????}); ???????????????})}); </script></html>登录的处理页面 dengluchuli.php
<?php $uid = $_POST["u"]; $pwd = $_POST["p"]; include("./DBDA.class.php"); $db = new DBDA(); $sql = "select password from login where username=’{$uid}’"; $mm = $db->StrQuery($sql,0); if($mm == $pwd && $pwd!=""){ echo "OK";} else { echo "NO";}3.用ajax验证用户名是否可用 testuid.php
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><script src="../jquery-1.11.2.min.js"></script><title>无标题文档</title></head><body><input type="text" id="uid" /><span id="ts"></span></body><script type="text/javascript"> $("#uid").blur(function(){//blur表示失去焦点时触发 ???????????????//取用户名 var uid = $("#uid").val(); //调ajax $.ajax({ ???????????url:"uidchuli.php", data:{u:uid}, type:"POST", dataType:"TEXT", success: function(data){ if(data>0) ???????????????????{ ???????????????????????$("#ts").html("该应户名已存在"); ???????????????????????$("#ts").css("color","red"); ???????????????????} else { ???????????????????????$("#ts").html("该应户名可用"); ???????????????????????$("#ts").css("color","green"); ???????????????????} ???????????????} ???????????????????????}); ???????????????}) </script></html>处理页面 uidchuli.php
<?php $uid = $_POST["u"]; include("./DBDA.class.php"); $db = new DBDA(); $sql = "select count(*) from login where username=’{$uid}’"; echo $db->StrQuery($sql,0);效果如图：
4.动态调用数据库，搜索框里输入关键字，内容中含关键字的自动出现在输入框下面。
list.php
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><script src="../jquery-1.11.2.min.js"></script><title>无标题文档</title></head><body><br /><div> ???<input type="text" id="name" /></div><div id="list"></div></body><script type="text/javascript"> $("#name").keyup(function(){ //取名称 var n = $(this).val(); if(n!="") ???{ //调ajx $.ajax({ ???????????url:"listchuli.php", data:{n:n}, type:"POST", dataType:"TEXT", success: function(data){ var sz = data.split("|"); var str = ""; for(var i=0;i<sz.length;i++) ???????????????{ ???????????????????str = str+"<div class=’l’>"+sz[i]+"</div>"; ???????????????} ???????????????$("#list").html(str); ???????????????????????????} ???????????????????}); ???????} else { ???????????$("#list").html(""); ???????} ???????}) </script></html>处理页面 listchuli.php
<?php $name = $_POST["n"]; include("./DBDA.class.php"); $db = new DBDA(); $sql = "select areaname from chinastates where areaname like’%{$name}%’"; echo $db->StrQuery($sql,0);效果如图：
使用PHP中的ajax做登录页面、验证用户名是否可用、动态调用数据库