在注册的时候验证用户名唯一性在数据库里~~谁能给个思路
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head>
<body>
<form id="form1" name="form1" method="post" action="zhucechenggong.asp">
<table width="247" border="1" align="center">
<tr>
<td colspan="2" align="center"><h4>用户注册</h4></td>
</tr>
<tr>
<td width="36">用户名:</td>
<td width="195"><input name="t1" type="text" id="t1" />
<input type="submit" name="Submit3" value="验证用户唯一" /></td>
</tr>
<tr>
<td>密码</td>
<td><input name="t2" type="password" id="t2" /></td>
</tr>
<tr>
<td>真实姓名</td>
<td><input name="t3" type="text" id="t3" /></td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" name="Submit" value="注册" />
<input type="reset" name="Submit2" value="重置" /></td>
</tr>
</table>
</form>
</body>
</html>