Add a default _count_string property
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index ebf828c..d5367b4 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -78,6 +78,13 @@
protected $_reserved_identifiers = array('*'); // Identifiers that should NOT be escaped
/**
+ * The syntax to count rows is slightly different across different
+ * database engines, so this string appears in each driver and is
+ * used for the count_all() and count_all_results() functions.
+ */
+ protected $_count_string = 'SELECT COUNT(*) AS ';
+
+ /**
* Constructor
*
* @param array