实现代码：

conn.php

??? <?php?
??? $conn = @ mysql_connect("localhost", "root", "") or die("数据库链接错误");?
??? mysql_select_db("form", $conn);?
??? mysql_query("set names 'gbk'");??
??? ?>
searchAndDisplayWithColor.php
?
?

??? <?php?
??? include 'conn.php';?
??? ?>?
??? <table width=500 align="center">?
???????? <form action="" method="get">?
???????? <tr>?
???????????? <td>关键字：<input type="text" name="keyWord" />?
???????????? <input type="submit" value="搜索" /></td>?
???????? </tr>?
???????? </form>?
???? </table>?
??????
???? <table width=500 border="0" align="center" cellpadding="5"
???????? cellspacing="1" bgcolor="#add3ef">?
???????? <?php?
???????? //关键字不为空的时候才执行相关搜索?
???????? if($_GET['keyWord']){?
???????? //用空格符把关键字分割开?
???????? $key=explode(' ', $_GET[keyWord]);?
???????? $sql="select * from message where title like '$key[0]' or title like '$key[1]' or content like '$key[0]' or content like '%$key[1]%'";?
???????? $query=mysql_query($sql);?
???????? while ($row=mysql_fetch_array($query)){?
???????????? //替换关键字，并且把关键字高亮显示?
???????????? $row[title]=preg_replace("/$key[0]/i", "<font color=red><b>$key[0]</b></font>", $row[title]);?
???????????? $row[title]=preg_replace("/$key[0]/i", "<font color=red><b>$key[1]</b></font>", $row[title]);?
???????????? $row[content]=preg_replace("/$key[0]/i", "<font color=red><b>$key[0]</b></font>", $row[content]);?
???????????? $row[content]=preg_replace("/$key[1]/i", "<font color=red><b>$key[1]</b></font>", $row[content]);?
???????????? ?>?
??????
???????? <tr bgcolor="#eff3ff">?
???????????? <td>标题：<font color="black"><?=$row[title]?></font> 用户：<font color="black"><?=$row[user] ?></font>?
???????????? <div align="right"><a href="preEdit.php?id=<?=$row[id]?>">编辑</a>&nbsp;&nbsp;|&nbsp;&nbsp;<a?
???????????????? href="delete.php?id=<?=$row[id]?>">删除</a></div>?
???????????? </td>?
???????? </tr>?
???????? <tr bgColor="#ffffff">?
???????????? <td>内容：<?=$row[content]?></td>?
???????? </tr>?
???????? <tr bgColor="#ffffff">?
???????????? <td>?
???????????? <div align="right">发表日期：<?=$row[lastdate]?></div>?
???????????? </td>?
???????? </tr>?
???????? <?php }?
???????? }?
???????? ?>?
???? </table>

说明：在这个小程序中，有一点不足之处在于，只能同时搜索两个关键字，并且中间用空格" "隔开，如果只是搜索一个关键字，如："大"
显示的时候会出现乱码 ……^|_|^,这是由于下面代码的结果：

???? //用空格符把关键字分割开?
???? $key=explode(' ', $_GET[keyWord]);

如果要改进的话，在这里的后面就要做一下判断了。