Phpsession application instance logon verification

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Login 
 
 
 
 
 


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@ Mysql_connect ("localhost", "root", "1981427") // you must connect to the database server before selecting a database.
Or die ("database server connection failed ");
@ Mysql_select_db ("test") // select the database mydb
Or die ("The database does not exist or is unavailable ");
// Obtain user input
$ Username = $ _ POST ['username'];
$ Passcode = $ _ POST ['passcode'];
// Execute an SQL statement to obtain the Session value
$ Query = @ mysql_query ("select username, userflag from users"
. "Where username = '$ username' and passcode =' $ passcode '")
Or die ("SQL statement execution failed ");
// Determine whether the user exists and the password is correct
If ($ row = mysql_fetch_array ($ query ))
{
Session_start (); // indicates the start of the Session.
// Determine whether the user's permission information is valid. if the value is 1 or 0, the permission information is valid.
If ($ row ['userflag'] = 1 or $ row ['userflag'] = 0)
{
$ _ SESSION ['username'] = $ row ['username'];
$ _ SESSION ['userflag'] = $ row ['userflag'];
Echo "Welcome to log on. Click here to enter the welcome page ";
}
Else // output error message if the permission information is invalid
{
Echo "incorrect user permission information ";
}
}
Else // if the user name and password are incorrect, an error is returned.
{
Echo "incorrect user name or password ";
}
?>

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Unset ($ _ SESSION ['username']);
Unset ($ _ SESSION ['passcode']);
Unset ($ _ SESSION ['userflag']);
Echo "logout successful ";
?>

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Session_start ();
If (isset ($ _ SESSION ['username'])
{
@ Mysql_connect ("localhost", "root", "1981427") // you must connect to the database server before selecting a database.
Or die ("database server connection failed ");
@ Mysql_select_db ("test") // select the database mydb
Or die ("The database does not exist or is unavailable ");
// Obtain the Session
$ Username = $ _ SESSION ['username'];
// Execute the SQL statement to obtain the userflag value
$ Query = @ mysql_query ("select userflag from users"
. "Where username = '$ username '")
Or die ("SQL statement execution failed ");
$ Row = mysql_fetch_array ($ query );
// Compare the permission information in the current database with that in the Session. if the permission information is different, update the Session information.
If ($ row ['userflag']! = $ _ SESSION ['userflag'])
{
$ _ SESSION ['userflag'] = $ row ['userflag'];
}
// Output different welcome information based on the Session value
If ($ _ SESSION ['userflag'] = 1)
Echo "welcome administrator". $ _ SESSION ['username']. "log on to the system ";
If ($ _ SESSION ['userflag'] = 0)
Echo "welcome". $ _ SESSION ['username']. "log on to the system ";
Echo "logout ";
}
Else
{
Echo "you are not authorized to access this page ";
}
?> I also reprinted other people's PHP for beginners. I haven't tested it on the computer yet. collect it first.

From: http://phpstart.php100.com/apps-htm-q-diary-a-detail-did-7373.html