代码PHP 设置用户登陆限制，3次错误锁定账户5分钟

if (mysqli_num_rows($r) == 1){
							$row = mysqli_fetch_array($r);

							if (SHA1($psword) == $row['psword']){
								session_start();
								
								//set session variables
								$_SESSION['uname'] = $uname;
								$_SESSION['fname'] = $row['fname'];
								setcookie('uname',$uname,time()+10);
								setcookie('fname',$row['fname'],time()+10);
								//check the role of user
								if($row['role'] == 'Student'){
									echo "";
									exit();
								}
								else
									header('LOACTION: admin.php');
							}
							else							
								echo "Incorrect password.";	
						}							
						else {
					 		echo "Unknown username.";
						}	 
					}