Merge pull request #4223 from j0inty/develop

CI_DB_driver->simple_query() to check initialize() return value
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index 0ea6794..25e70ec 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -774,7 +774,10 @@
 	{
 		if ( ! $this->conn_id)
 		{
-			$this->initialize();
+			if ( ! $this->initialize())
+			{
+				return FALSE;
+			}
 		}
 
 		return $this->_execute($sql);