Fix on _update_batch() : wrong variable used for field selection
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index 20b7867..0317408 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -529,7 +529,7 @@
 		$cases = '';
 		foreach ($final as $k => $v)
 		{
-			$cases .= $k.' = (CASE '.$k."\n"
+			$cases .= $k.' = (CASE '.$index."\n"
 				.implode("\n", $v)."\n"
 				.'ELSE '.$k.' END), ';
 		}