MySQL database user authentication system code written in PHP_PHP tutorial

In the past two days, I was asked by a friend to help him write a user authentication system using the MySQL database. Of course I couldn't shirk it, so I had to spend a whole night's rest and write a very simple PHP program.
The principle of user authentication is very simple: first, the user needs to fill in the user name and password on the page. Of course, unregistered users need to register first. Then call the database to search whether there is a corresponding user. If yes, confirm it; if not, remind the user to register first. It's easy to do all this using PHP, but it should be noted that if I want to confirm the user's identity on subsequent pages, using PHP3 I can only figure out how to use cookies. If you want to use session, you can only wait for the official version of PHP4 to be released!
The first step is to create a login page, so I won’t go into details here. I just made a very simple one, you can make it more beautiful.
The second step begins with the design of the confirmation program after login.
login.php:

Copy code The code is as follows:

mysql_connect("localhost","user", "password")
/*Connect to the database, change the username and password yourself*/
or die("Unable to connect to the database, please try again");
mysql_select_db("userinfo")
or die ("Unable to select database, please try again");
$today=date("Y-m-d H:i:s");
$query="
select id
from usertbl
where name=$name and password=$password
/*Search and log in the user’s corresponding information from the database*/
";
$result=mysql_query($query);
$numrows= mysql_num_rows($result);
if($numrows==0){
/*Verify whether the user with the same information can be found, if not, it will not be registered*/
echo Illegal user

echo Please register first

echo Retry

}
else{
$row=mysql_fetch_array($result);
$id=$row[0];
$query="
update usertbl
set lastlogin=$today
where id=$id";
$result=mysql_query($query);
SetCookie("usercookie" , "Welcome, $name");
/*Cookies are used here to facilitate subsequent page authentication.
But I haven’t finished developing this area yet. I hope anyone who is interested can correct me*/
echo Login successful

echo Please come in!

}
?>

The third step is of course to prepare the registration page, which I won’t go into details.
The fourth step is to confirm your identity after registration and enter it into the database.
register.php:

Copy code The code is as follows:

mysql_connect("localhost","user"," password") /*Please change the username and password*/
or die("Unable to connect to the database, please try again");
mysql_select_db("userinfo")
or die("Unable to select the database, please try again"); Try again");
$query="select id from usertbl where name=$name";
/*Search for user information with the same name from the database*/
$result=mysql_query($query) ;
$numrows=mysql_num_rows($result);
if($numrows!=0) /*If you find it, of course someone has registered the same name first*/
{echo Someone has already registered this name. Please reselect your name!;} 
else 
{$query="insert into usertbl values(0,$name,$password,)";
/*If you can’t find the same one, enter a new user Information*/
mysql_query($query);
echo Registration successful;
echo Please log in!;}
?>

The next step is the use of cookies, I originally planned to Use cookies to identify users on each page, but since other pages have not been completed yet, I don’t know what information is needed. So there is only a very simple use, using php reference here:

Copy code The code is as follows:

if(!$usercookie )
{header("Illegal user");
}
?>
welcome.php:
require("cookie.php"); /*Calling cookie.php*/
?>
echo $usercookie;
?>

At this point, a very simple user authentication system has been completed. Of course, if you want to use it, you must build a database. The following is the structure of my database table. The name of the library is userinfo.

Copy code The code is as follows:

create table usertbl
(
ID int auto_increment primary key,
Name varchar(30),
Password varchar(20),
Lastlogin varchar(20)
);

http://www.bkjia.com/PHPjc/318253.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/318253.htmlTechArticleIn the past two days, I was entrusted by a friend to help him write a user authentication system using the MySQL database. Of course I couldn't shirk it, so I had to spend a whole night's rest and write a very simple...