Get id of last post displayed in table - php

Question

In code below I will be displaying posts in table. Now for creating load more function I need to get id of last post in table but I am not able to do that, Here $ID = $row['id']; gets me id of first post may be because it's outside loop and to get id of last post I must place this code inside loop. But where to exactly place it so that I get id of last post displayed in table.
<?php
$sql = "SELECT * FROM posts ORDER BY id desc limit 3";
$query = $db->prepare($sql);
$query->execute();
$row = $query->fetch(PDO::FETCH_ASSOC);
$ID = $row['id'];
?>
<table>
<tr>
<?php do { //horizontal looper?>
<td>
<div><h2><?php echo $row['title']; ?></h2></div>
<div><p><?php echo $row['body']; ?></p></div>
<img src='<?php echo $row['pic']; ?>'>
<div><p><?php echo $row['about']; ?></p></div>
</td>
<?php
$row = $query->fetch(PDO::FETCH_ASSOC);
if (!isset($nested_List)) {
$nested_List= 1;
}
if (isset($row) && is_array($row) && $nested_List++%3==0) {
echo "</tr><tr>";
}
} while ($row); //end horizontal looper
?>
</table>

Answer 1

Try this code :-
$ID1 = $row[0]['id'];//first id of table
$ID2 = $row[1]['id'];//2 id of table
$ID3 = $row[2]['id'];//3 id of table
get latest id:-
$sql = "SELECT * FROM posts ORDER BY id desc limit 1";

Answer 2

Try This Query
<?php
try {
$dbh = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
$stmt = $dbh->prepare("INSERT INTO test (name, email) VALUES(?,?)");
try {
$dbh->beginTransaction();
$tmt->execute( array('user', 'user#example.com'));
$dbh->commit();
print $dbh->lastInsertId();
} catch(PDOExecption $e) {
$dbh->rollback();
print "Error!: " . $e->getMessage() . "</br>";
}
} catch( PDOExecption $e ) {
print "Error!: " . $e->getMessage() . "</br>";
}
?>