Since the data is already in the tables for students and sports, this information can be queried with some select statements in order to populate some HTML dropdowns. The advantage of using the select queries and the dropdowns is that value of the options can be set to the database ID while showing the user the human-readable text. Then, the page just needs to monitor for the form's submission and insert the IDs from the dropdowns along with the performance metric. I have not tested the code below, but here is a quicky example of how that might work.
Note: I like the PDO interface for preparing SQL queries in order to prevent injection attacks.
<?php
$user = 'user';
$password = 'password';
$con = new PDO('mysql:dbname=dbname;host=127.0.0.1;chartset=urf8', $user, $password);
$student_stmt = $con->prepare('select * from students');
$student_stmt->execute();
$sport_stmt = $con->prepare('select * from sports');
$sport_stmt->execute();
if (isset($_GET['student']) && isset($_GET['sport']) && isset($_GET['value'])) {
$student = $_GET['student'];
$sport = $_GET['sport'];
$value = $_GET['value'];
$insert_stmt = $con->prepare('insert into preformances (sport_id, student_id, value) values (:sport_id, :student_id, :value)');
$insert_stmt->bindParam(':sport_id', $sport);
$insert_stmt->bindParam(':student_id', $student);
$insert_stmt->bindParam(':value', $value);
$insert_stmt->execute();
}
?>
<html>
<head>
<title>Form</title>
</head>
<body>
<form action="self.php" method="get">
Student:
<select name="student">
<?php while ($row = $student_stmt->fetch(PDO::FETCH_ASSOC)) { ?>
<option value="<?php echo $row['id']; ?>"><?php echo $row['firstname'] . " " . $row['lastname']; ?></option>
<?php } ?>
</select>
Sport:
<select name="sport">
<?php while ($row = $sport_stmt->fetch(PDO::FETCH_ASSOC)) { ?>
<option value="<?php echo $row['sport_id']; ?>"><?php echo "$row['sportname']"; ?></option>
<?php } ?>
</select>
Performance: <input name="value" type="text" />
<button type="submit">Submit</button>
</form>
</body>
</html>
Edit:
Made the changes in the code in the suggested comment.
