Teach you how to write a MySQL database user authentication system using PHP

Teach you how to write a MySQL database user authentication system using PHP_PHP Tutorial

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Release： 2016-07-13 17:03:38

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In the past two days, I was asked by a friend to help him write a user authentication system using a 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 very simple to use PHP to accomplish all this, 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, which 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:?
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 users with the same information can be found, if not, they are not 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 friends who are interested can correct me*/
echo Login successful
;
echo Please come in!
;
}