title: Need to figure out total hours between check-in and check-out times
body: <p>I am trying to create a check-in/check-out table in my database. My check-in form works without issue, inserting the time into my database. The problem occurs when I try to check out. Everything is good on the first entry...</p>
  
  <p><a href="https://i.stack.imgur.com/iDNWp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iDNWp.png" alt="enter image description here"></a></p>
  
  <p>But when I try to check in and check out again, this happens...</p>
  
  <p><a href="https://i.stack.imgur.com/MsqH5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MsqH5.png" alt="enter image description here"></a></p>
  
  <p>So far so good, but when I check out...</p>
  
  <p><a href="https://i.stack.imgur.com/7TmGe.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7TmGe.png" alt="enter image description here"></a>
  Currently, my code updates the <code>out</code> column and <code>totalTime</code> column of all matching <code>child_id</code>'s.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>// Select the correct child from the database
  $sql_childID = "SELECT id FROM child
                  WHERE firstName = '$childFirstName'
                  AND lastName = '$childLastName'";
  $result = $pdo-&gt;query($sql_childID);
  $row = $result-&gt;fetch();
  $var = $row['id'];
  
  // Insert the check out time for the child
  $query = "UPDATE checkinout
          SET `out` = :nowTime
          WHERE child_id = $var
          AND `in` IS NOT NULL";
  $statement = $pdo-&gt;prepare($query);
  $statement-&gt;bindValue(':nowTime', date("YmjHis"));
  $statement-&gt;execute();
  
  // Select check in time for specified child
  $sql_inTime = "SELECT `in` FROM checkinout
          WHERE child_id = $var";
  $inResult = $pdo-&gt;query($sql_inTime);
  $inRow = $inResult-&gt;fetch();
  $inTime = strtotime($inRow['in']);
  
  // Select the check out time for specified child
  $sql_outTime = "SELECT `out` FROM checkinout
          WHERE child_id = $var";
  $outResult = $pdo-&gt;query($sql_outTime);
  $outRow = $outResult-&gt;fetch();
  $outTime = strtotime($outRow['out']);
  
  // Find total hours
  $totalTime = abs($outTime - $inTime)/(60*60);
  
  // Update totalHours column for specified child
  $queryTotalTime = "UPDATE checkinout
                  SET totalTime = :totalTime
                  WHERE child_id = $var
                  AND 'out' IS NOT NULL";
  $statement = $pdo-&gt;prepare($queryTotalTime);
  $statement-&gt;bindValue(':totalTime', $totalTime);
  $statement-&gt;execute();
  </code></pre>