diff --git a/sql/db_create_sqlite.sql b/sql/db_create_sqlite.sql
index d163c5b..1b4973c 100644
--- a/sql/db_create_sqlite.sql
+++ b/sql/db_create_sqlite.sql
@@ -143,10 +143,12 @@ drop table if exists user_stat;
 create table user_stat
 (
 user_id         int PRIMARY KEY,
+user_limit      int NOT NULL,
 user_usedspace  int NOT NULL DEFAULT 0,
 user_bookcount  int NOT NULL DEFAULT 0,
 user_doccount   int NOT NULL DEFAULT 0,
 user_notecount  int NOT NULL DEFAULT 0,
-CONSTRAINT `fk_user_stat_user` FOREIGN KEY (`user_id`) REFERENCES user(`user_id`) ON DELETE RESTRICT
+CONSTRAINT `fk_user_stat_user` FOREIGN KEY (`user_id`) REFERENCES user(`user_id`) ON DELETE RESTRICT,
+CONSTRAINT `ck_usedspace` CHECK (user_usedspace <= user_limit)
 );
--- insert into user_stat values (1,1,1,1,1);
\ No newline at end of file
+-- insert into user_stat values (1,1,1,1,1,1);
\ No newline at end of file
diff --git a/sql/trigger_sqlite.sql b/sql/trigger_sqlite.sql
index 98fa53c..70e1ecc 100644
--- a/sql/trigger_sqlite.sql
+++ b/sql/trigger_sqlite.sql
@@ -2,7 +2,7 @@ drop trigger if exists `trig_create_user_stat`;
 create trigger `trig_create_user_stat` 
     after insert on user
     for each row begin
-    insert into user_stat (`user_id`) values(NEW.user_id);    
+    insert into user_stat (`user_id`, `user_limit`) values(NEW.user_id, NEW.user_limit);
 end;
 
 drop trigger if exists `trig_delete_user_stat`;
diff --git a/表设计.xlsx b/表设计.xlsx
index 24740fc..1bfad03 100644
Binary files a/表设计.xlsx and b/表设计.xlsx differ