Developing a Login System with PHP and MySQL
By daBoss2005-05-31
Component 2 Verification and Authentication
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A registered user will want to log into the system to access the functionality provided by the website. The user will have to provide his login id and password for the system to verify and authenticate.
This is typically done through a simple HTML form. This HTML form typically contains 2 fields and 2 buttons:
1. A login id field
2. A password field
3. A Submit button
4. A Reset button
Assume that such a form is coded into a file named authenticate.html. The following HTML code excerpt is a typical example. When the user has filled in all the fields, the authenticate.php page is called when the user clicks on the Submit button.
[form name="authenticate" method="post" action="authenticate.php"]
[input name="login id" type="text" value="loginid" size="20"/][br]
[input name="password" type="text" value="password" size="20"/][br]
[input type="submit" name="submit" value="submit"/]
[input type="reset" name="reset" value="reset"/]
[/form]
The following code excerpt can be used as part of authenticate.php to process the login request. It connects to the MySQL database and queries the table used to store the registration information.
@mysql_connect("localhost", "mysql_login", "mysql_pwd") or die("Cannot connect to DB!");
@mysql_select_db("tbl_login") or die("Cannot select DB!");
$sql="SELECT loginid FROM login_tbl WHERE loginid=".$loginid. and password=.$password.;
$r = mysql_query($sql);
if(!$r) {
$err=mysql_error();
print $err;
exit();
}
if(mysql_affected_rows()==0){
print "no such login in the system. please try again.";
exit();
}
else{
print "successfully logged into system.";
//proceed to perform websites functionality e.g. present information to the user
}
As in component 1, the code excerpt assumes that the MySQL table that is used to store the registration data is named tbl_login and contains 3 fields the loginid, password and email fields. The values of the $loginid and $password variables are passed in from the form in authenticate.html using the post method.
Tutorial Pages:
» Developing a Login System with PHP and MySQL
» Component 1 Registration
» Component 2 Verification and Authentication
» Component 3 Forgot Password
» Conclusion
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