diff --git a/PostgreSQL/prism/prism.sql b/PostgreSQL/prism/prism.sql
index b09bbb0..ec289c5 100644
--- a/PostgreSQL/prism/prism.sql
+++ b/PostgreSQL/prism/prism.sql
@@ -10,6 +10,7 @@ from activities;
 -- 数据总量
 select max(activity_id) - min(activity_id) + 1
 from activities;
+select count(*) from activities;
 
 -- 1天内的数据，按action分组排序
 select b.action_id, b.action, count(b.action_id)