Can you please explane this assignment? It gave me error?

You must enter your first and last name! Click your browser's Back button to return to the Guest Book form.

"; else { $DBConnect = @mysql_connect("host", "user", "password"); if ($DBConnect === FALSE) echo "

Unable to connect to the database servr.

" . "

Error code " . mysql_errno() . ":" . mysql_errno(). "

";

else { $DBName = "guestbook"; if (!@mysql_select_db($DBName, $DBConnect)){ $SQLstring = "CREATE DATABASE $DBName"; $QueryResult = @mysql_query($SQLstring, $DBConnect); if ($QueryResult === FALSE) echo "

Unable to execute the query.

" ."

Error code" . mysql_errno($DBConnect) . ":" .mysql_error($DBConnect). "

"; else echo "

You are the first visitor!

"; } mysql_select_db($DBName, $DBConnect);

$TableName = "visitors"; $SQLstring = "SHOW TABLES LIKE '$TableName'"; $QueryResult = @mysql_query($SQLstring, $DBConnect); if (mysql_num_rows($QueryResult) == 0) { $SQLstring = "CREATE TABLE $TableName (countID SMALLINT NOT NULL AUTO_INCEMENT PRIMARY KEY, last_name VARCHAR(40), first_name VARCHAR(40))"; $QueryReult = @mysql_query($SQLstring, $DBConnect); if ($QueryResult===FALSE) echo "

Unable to create the table.

" . "

Error code " . mysql_errno($DBConnect) . ":" . mysql_error($DBConnect). "

"; $LastName = stripslashes($_POST['last_name']); $FirstName = stripslashes($_POST['first_name']); $SQLstring = "INSERT INTO $TableName VALUES(NULL, 'LastName','$FirstName')"; $SQLstring = @mysql_query($SQLstring, $DBConnect); if ($QueryResult === FALSE) echo "

Unable to execute the query.

" . "

Error code" . mysql_errno($DBConnect) . ":" . mysql_error($DBConnect). "

"; else echo "

Thank you signing our guest book!

"; } mysql_close($DBConnect) } } ?>