Learn php(3) in ten days_PHP tutorial-PHP Tutorial-php.cn

第七天学习目的：学会SESSION的使用

SESSION的作用很多，最多用的就是站点内页面间变量传递。在页面开始我们要session_start();开启SESSION；
然后就可以使用SESSION变量了，比如说要赋值就是：$_SESSION['item']="item1";要得到值就是$item1=$_SESSION['item'];，很简单吧。这里我们可能会使用到一些函数，比如说判断是不是某SESSION变量为空，可以这么写：empty($_SESSION['inum'])返回true or false。

下面综合一下前面所说的我们来看一个登陆程序，判断用户名密码是否正确。
登陆表单是这样：login.php

Administrators Login
Username
Password

处理文件是这样
require_once('conn.php');
session_start();
$username=$_POST['username'];
$password=$_POST['password'];
$exec="select * from admin where username='".$username."'";
if($result=mysql_query($exec))
{
  if($rs=mysql_fetch_object($result))
  {
    if($rs->password==$password)
    {
      $_SESSION['adminname']=$username;
      header("location:index.php");
    }
    else
    {
      echo "<script>alert('Password Check Error!');location.href='login.php';</script>";
    }
  }
  else
  {
  echo "<script>alert('Username Check Error!');location.href='login.php';</script>";
  }
  }
else
{
echo "<script>alert('Database Connection Error!');location.href='login.php';</script>";
} ?>

conn.php是这样：
$conn=mysql_connect ("127.0.0.1", "", "");
mysql_select_db("shop");
?>

由于 $_SESSION['adminname']=$username;我们可以这样写验证是否登陆语句的文件：checkadmin.asp
session_start();
if($_SESSION['adminname']=='')
{
echo "<script>alert('Please Login First');location.href='login.php';</script>";
}
?>

呵呵，今天说到这里，明天说一下怎么弄一个分页。第八天学习目的：做一个分页显示

关键就是用到了SQL语句中的limit来限定显示的记录从几到几。我们需要一个记录当前页的变量$page，还需要总共的记录数$num

对于$page如果没有我们就让它=0，如果有<0就让它也=0，如果超过了总的页数就让他=总的页数。

$execc="select count(*) from tablename ";
$resultc=mysql_query($execc);
$rsc=mysql_fetch_array($resultc);
$num=$rsc[0];

这样可以得到记录总数
ceil($num/10))如果一页10记录的话，这个就是总的页数

所以可以这么写
if(empty($_GET['page']))
{
$page=0;
}
else
{
$page=$_GET['page'];
if($page<0)$page=0;
if($page>=ceil($num/10))$page=ceil($num/10)-1;//因为page是从0开始的，所以要-1
}

这样$exec可以这么写 $exec="select * from tablename limit ".($page*10).",10";
//一页是10记录的

最后我们需要做的就是几个连接：
FirstPage
PrevPage
NextPage
LastPage

这是一个大致的思路，大家可以想想怎么来优化？今天说到这里，明天说一下一些注意的问题。
第九天学习目的：注意事项

因为我是先学ASP的，所以再做PHP的时候会发现很多地方需要适应。

1、注意不要漏了分号
2、注意不要漏了变量前的$
3、使用SESSION的时候注意不要遗漏session_start();

如果发生错误的时候，可以采用以下方法：
1、如果是SQL语句出错，就注释了然后输出SQL语句，注意也要注释调后续的执行SQL语句
2、如果是变量为空，大多是没有传递到位，输出变量检查一下，检查一下表单的id和name
3、如果是数据库连接出错，检查是否正确打开MY SQL和是否遗漏了连接语句
4、注意缩进，排除括号不区配的错误

在做大网站的时候，我的思路是先构建数据库，确定每一个字段的作用，和表之间的关系。然后设计后台界面，从添加数据开始做起，因为添加是否成功可以直接到数据库里面验证，做好了添加再做显示的页面，最后才是两者的结合。一般来说后台就包括添加删除修改和显示，后台没有问题了，前台也没有什么大问题。前台还需要注意安全性和容错还有就是输出格式。

好了，今天说到这里，明天说一下如果用PHP上传文件和发邮件。
Day 10 Learning purpose: Learn to use PHP to upload files and send emails

The file upload form must add enctype="multipart/form-data"
and Look at the code below:

$f=&$HTTP_POST_FILES['file'];
$dest_dir='uploads';//Set the upload directory
$dest=$ dest_dir.'/'.date("ymd")."_".$f['name'];//I set the file name here plus the date plus the file name to avoid duplication
$r=move_uploaded_file($f ['tmp_name'],$dest);
chmod($dest, 0755);//Set the attributes of the uploaded file

The name of the uploaded file is date("ymd")."_ ".$f['name'] can be used when inserting into the database later. PHP actually moves the file you uploaded from the temporary directory to the specified directory. move_uploaded_file($f['tmp_name'],$dest); This is the key

As for sending emails, it is even simpler. You can use the mail() function

mail("recipient address" ,"Subject","Text","From: sender rnReply-to: sender's address");

However, mail() requires server support, and SMTP server needs to be configured under WINDOWS , Generally speaking, any external LINUX space will work.
It seems that uploading files and sending emails is much simpler than ASP. You only need to call functions. ASP also needs to use different components of the server such as FSO, JMAIL and so on.

That’s it for learning PHP in ten days. My three major series of articles all use “Learning in Ten Days” as their names. What I want to tell you is that getting started with ASP, PHP, and ASP.NET can all take ten days. But mastery is by no means ten days, and everyone still needs to study it by themselves.
Learning purpose: Learn to use PHP to upload files and send emails

The upload file form must add enctype="multipart/form-data"
and
Look at the code below:

$f=&$HTTP_POST_FILES['file'];
$dest_dir='uploads';//Set the upload directory
$ dest=$dest_dir.'/'.date("ymd")."_".$f['name'];//I set the file name here with the date plus the file name to avoid duplication
$r=move_uploaded_file ($f['tmp_name'],$dest);
chmod($dest, 0755);//Set the attributes of the uploaded file

The name of the uploaded file is date("ymd") ."_".$f['name'] can be used when inserting into the database later. PHP actually moves the file you uploaded from the temporary directory to the specified directory. move_uploaded_file($f['tmp_name'],$dest); This is the key

As for sending emails, it is even simpler. You can use the mail() function

mail("recipient address" ,"Subject","Text","From: sender rnReply-to: sender's address");

However, mail() requires server support, and SMTP server needs to be configured under WINDOWS , Generally speaking, any external LINUX space will work.
It seems that uploading files and sending emails is much simpler than ASP. You only need to call functions. ASP also needs to use different components of the server such as FSO, JMAIL and so on.

That’s it for learning PHP in ten days. My three major series of articles all use “Learning in Ten Days” as their names. What I want to tell you is that getting started with ASP, PHP, and ASP.NET can all take ten days. But mastery is by no means ten days, and everyone still needs to study it by themselves.