session_start();
?>
//_SESSION['sys_user_id'] 是通过session获得登录时用户的ID即user_id。
//Function:连接数据库 
//数据库:inv ,用户:root, 密码:831025
function db_link()
{
 access_id = "root";
 db_name = "inv";
 @ db = mysql_connect('localhost', access_id, '831025') or 
 die("Could not connect to database. ");
 mysql_query("SET NAMES 'GBK'");//显示中文
 mysql_select_db(db_name);
 return db;
}
link=db_link();
//Funtion:根据用户ID,获得用户name
//表:sys_user 字段:user_id,user_name,user_real_name,user_muser,user_mdate...
function get_user(user_id, user_field)
{
 if (user_id == 0 && (user_field == "user_name" || user_field == "user_real_name"))
 return "none";
 else {
 user_sql = "SELECT ".user_field." FROM sys_user WHERE user_id = ".user_id;
 user_res = mysql_query(user_sql);
 user_num = mysql_num_rows(user_res);
 if (user_num > 0) {
 user_row = mysql_fetch_array(user_res);
 return user_row[0];
 }
 else
 return "";
 }
}
echo '
';
if (_POST['save'] == 'Save') {
 curr_pwd = _POST['curr_pwd']; //用户输入的原始密码
 new_pwd = _POST['new_pwd']; //用户输入的新密码
 renew_pwd = _POST['renew_pwd']; 
 
 //从数据库获得用户真正的原始密码
 user_curr_sql = "SELECT user_password FROM sys_user WHERE user_id = '"._SESSION['sys_user_id']."' ";
 user_curr_res = mysql_query(user_curr_sql);
 user_curr_row = mysql_fetch_array(user_curr_res);
 user_curr_pwd = user_curr_row['user_password'];
 
 //对用户输入的原始密码用password进行加密,以便和真正的原始密码进行比较
 user_encode_pwd = "SELECT password(curr_pwd);";
 user_encode_res = mysql_query(user_encode_pwd);
 user_encode_row = mysql_fetch_array(user_encode_res);
 user_encode_pwd = user_encode_row[0];
 //比较用户输入的原始密码和从数据库中取得的原始密码
 if(user_encode_pwd != user_curr_pwd){
 //原始密码错误
 echo '';
 }else{
 //原始密码正确则修改用户密码
 user_pwd_sql = "UPDATE sys_user SET user_password=password('".new_pwd."'),user_muser='"._SESSION['sys_user_id']."',user_mdate=now() WHERE user_id = '"._SESSION['sys_user_id']."' ";
 user_pwd_res = mysql_query(user_pwd_sql);
 if (user_pwd_res) {
 echo '';
 }else {
 echo '';
 }
 }
}
?> 
来源:CSDN