Handle paging for entries with identical date

Paging now works even when many entries have the same date.
SQL speed could probably be improved by testing first on date, and then
on CONCAT.
Also, having an index on date would probably help too.

app/models/Entry.php

@@ -381,8 +381,8 @@ class EntryDAO extends Model_pdo {
 		} elseif ($state == 'read') {
 			$where .= ' AND is_read = 1';
 		}
-		if (!empty($limitFromId)) {
-			$where .= ' AND date ' . ($order === 'low_to_high' ? '<=' : '>=') . ' (SELECT date from freshrss_entry WHERE id = "' . $limitFromId . '")';
+		if (!empty($limitFromId)) {	//TODO: Consider using LPAD(e.date, 11)	//CONCAT is for cases when many entries have the same date
+			$where .= ' AND CONCAT(e.date, e.id) ' . ($order === 'low_to_high' ? '<=' : '>=') . ' (SELECT CONCAT(s.date, s.id) from freshrss_entry s WHERE s.id = "' . $limitFromId . '")';
 		}
 
 		if ($order == 'low_to_high') {
@@ -393,7 +393,7 @@ class EntryDAO extends Model_pdo {
 
 		$sql = 'SELECT e.* FROM ' . $this->prefix . 'entry e'
 		     . ' INNER JOIN  ' . $this->prefix . 'feed f ON e.id_feed = f.id' . $where
-		     . ' ORDER BY date' . $order . ', id' . $order;
+		     . ' ORDER BY e.date' . $order . ', e.id' . $order;
 
 		if (!empty($limitCount)) {
 			$sql .= ' LIMIT ' . ($limitCount + 2);	//TODO: See http://explainextended.com/2009/10/23/mysql-order-by-limit-performance-late-row-lookups/