Track/Verify/Update a MySQL result by user - php

Question

I have a database of a schedule where volunteers can check their shifts. I'm going to email them a link to the page where they enter their email addresses into an HTML form to access this information.
Is there a way I can track which emails are queried so I can resend the schedule link to those who haven't accessed the database?
If necessary, I could add an additional 'confirmed' check box to the results and have that update the database. I like that idea, but I'm not sure how to implement (or the terminology for what that action would be).
Edit: Here's the code I'm using to implement. However I'm not getting results in the confirmed column.
$db = new mysqli("host", "user", "pass", "db");
$stmt = $db->prepare('UPDATE volConfirm SET confirmed = TRUE WHERE email = ?');
$stmt->bind_param('s', $_POST['email']);
$stmt->execute();
$stmt = $db->prepare('SELECT * from volConfirm WHERE email = ?');
$stmt->bind_param('s', $_POST['email']);
$result = $stmt->get_result();
while ($row = $result->fetch_array(MYSQLI_NUM)) {
// construct your output here using $row to access database record
echo "<h2>" . $row['agreeName'] . "</h2>";
echo "<p> You have been assigned as a volunteer for:" . $row['position'] . "</p>";
echo "<p>Your shift times are scheduled for:" . $row['shift_times'] . "</p>";
echo "<p>Your shift has been confirmed:" . $row['confirmed'] . "</p>";
}

Answer 1

You need to do something along the lines of:
Add a new column to your volunteers table
ALTER TABLE Volunteers ADD COLUMN Confirmed BOOLEAN NOT NULL DEFAULT FALSE;
Have the PHP in the submission page update that column:
UPDATE Volunteers SET Confirmed = TRUE WHERE Email = 'foo#bar.com';
In your code snippet:
$db = new mysqli("dbhostname", "username", "password", "dbschema");
$stmt = $db->prepare('UPDATE volConfirm SET confirmed = TRUE WHERE email = ?');
$stmt->bind_param('s', $_POST['email']);
$stmt->execute();
$stmt = $db->prepare('SELECT * from volConfirm WHERE email = ?');
$stmt->bind_param('s', $_POST['email']);
$result = $stmt->get_result();
while ($row = $result->fetch_array(MYSQLI_NUM)) {
// construct your output here using $row to access database record
}
At some point in the future, get a list of all users who have not yet accessed the page:
SELECT Email FROM Volunteers WHERE Confirmed = FALSE;