<form action="index.php" method="get">
No sem: <input type="text" name="semnum">
<input type="submit" name="submit">
</form>

<?php

 //db info needed to connect
	$servername = "localhost";
	$username = "root";
	$password = "";
	$dbname = "data";

 if(isset($_GET['submit']))
 {
	 $semnum = $_GET['semnum'];

	//INPUT FORM
	echo "<form method='post'>";
	for ($i = 1; $i <= $semnum; $i++)
	{

		echo "
			<table border='1px'>
		   <br><br>
			<tr>
				<th colspan='2'>Sem $i </th>
			<tr>
				<th>Course Code</th>
				<th>Grade</th>
			</tr>
			";

		for ($z = 0; $z < 5; $z++)
		{

			echo "
				<tr>

					<td><input type='text' name='course_code[$i][$z]' ></td>
					<td><input type='text' name='course_grade[$i][$z]' ></td>

				</tr>
			 ";
		 }

		  echo "</table>";
	}

	echo "<br><input type='submit' name='submit'>";
	echo "</form>";


	//PROCESS
	if(isset($_POST['submit']))
	{
		//value received in array
		$course_code_arr = $_POST['course_code'];
		$course_grade_arr = $_POST['course_grade'];


		//implode jadi string
		$course_code = array();
		$course_grade = array();
		$course_code[1]=$course_grade[1]=$course_code[2]=$course_grade[2]=$course_code[3]=$course_grade[3]=$course_code[4]=$course_grade[4]=$course_code[5]=$course_grade[5]=$course_code[6]=$course_grade[6] = "";
		for ($i = 1; $i <= $semnum; $i++)
		{
			$course_code[$i] = implode(",",$course_code_arr[$i]);
			$course_grade[$i] = implode(",",$course_grade_arr[$i]);
		}

		try
		{
			//connect to database
			$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
			$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

			//insert data into db
			$stmt = $conn->prepare("INSERT INTO STUDENTS (`COURSE_SEM1`,`GRADE_SEM1`,`COURSE_SEM2`,`GRADE_SEM2`,
											`COURSE_SEM3`,`GRADE_SEM3`,`COURSE_SEM4`,`GRADE_SEM4`,`COURSE_SEM5`,`GRADE_SEM5`,
											`COURSE_SEM6`,`GRADE_SEM6`) VALUES(?,?,?,?,?,?,?,?,?,?,?,?);");

			//execute sql query
			$stmt->execute(array($course_code[1],$course_grade[1],$course_code[2],$course_grade[2],$course_code[3],$course_grade[3],
											$course_code[4],$course_grade[4],$course_code[5],$course_grade[5],$course_code[6],$course_grade[6]));

			echo "<script>alert('Success! Data Inserted.')</script>";



			//get balik dari db. patut buat while mcm biasa la. tpi ni 1 data ja so aku x while.
			$stmt2 = $conn->prepare("SELECT * FROM STUDENTS");
			$stmt2->execute();
			$result = $stmt2->fetch(PDO::FETCH_ASSOC);

			//So bila nak get balik data tu dari DB, akan bentuk string la, so nak kena explode() masuk array balik untuk guna
			for ($i = 1; $i <= $semnum; $i++)
			{
				$kos = "COURSE_SEM".$i;
				$gred = "GRADE_SEM".$i;
				$course_codeArray[$i] = explode(",",$result[$kos]);
				$course_gradeArray[$i] = explode(",",$result[$gred]);
			}

			echo "<br><h3>Contoh data bila nak display balik</h3>";

			for ($i = 1; $i <= $semnum; $i++)
			{
				echo "
				   <br><br>
					<table border='1px'>
					<tr>
						<th colspan='2'>Sem $i </th>
					<tr>
						<th>Course Code</th>
						<th>Grade</th>
					</tr>
					";

				for ($z = 0; $z < 5; $z++)
				{

					echo "
						<tr>

							<td>".$course_codeArray[$i][$z]."</td>
							<td>".$course_gradeArray[$i][$z]."</td>

						</tr>
					 ";
				 }

				  echo "</table>";
			}

		}
		catch(PDOException $e)
		{
			echo "Connection failed: " . $e->getMessage();
		}


	 //close conection
		$conn = null;
	}
 }

?>