Make db_select() clear cached database metadata
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index 06c3418..f52163c 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -256,6 +256,7 @@
 		if ($this->conn_id->select_db($database))
 		{
 			$this->database = $database;
+			$this->data_cache = array();
 			return TRUE;
 		}