Menambahkan fitur error pada sign up jika data form yang diisikan tidak lengkap

login/sign_up.html

@@ -9,6 +9,7 @@
 		<h1>-- Sign up --</h1>
 
 		<div>
+            <p id="error_signup" style="text-align: center;"></p>
 			<form name="sign_up" method="post" action="sign_up.php" onsubmit="return validate_password();">
 				Your name*
 				<input type="text" name="full_name"><br/>

login/sign_up.php

@@ -30,5 +30,12 @@
             }
             mysql_close($conn);
         }
+        else {
+            include("sign_up.html");
+            echo "<script>
+            document.getElementById('error_signup').innerHTML = 'Please fill all the required field';
+            </script>";
+            header("Location: sign_up.html");
+        }
     }
 ?>