diff --git a/db/.gitignore b/db/.gitignore
new file mode 100644
index 0000000..3c3629e
--- /dev/null
+++ b/db/.gitignore
@@ -0,0 +1 @@
+node_modules
diff --git a/db/build_db.js b/db/build_db.js
index 232d8c6..1c11451 100755
--- a/db/build_db.js
+++ b/db/build_db.js
@@ -83,7 +83,7 @@ for (var i = 0, count = categories.length; i < count; ++i) {
 //
 
 conn.query('DROP TABLE IF EXISTS history');
-conn.query('CREATE TABLE history(date DATETIME NOT NULL, reviewId INT NOT NULL, id INT NOT NULL AUTO_INCREMENT PRIMARY KEY)');
+conn.query('CREATE TABLE history(date DATETIME NOT NULL, reviewId INT NOT NULL, id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, FOREIGN KEY(reviewId) REFERENCES reviews(id))');
 
 
 //
@@ -91,7 +91,7 @@ conn.query('CREATE TABLE history(date DATETIME NOT NULL, reviewId INT NOT NULL,
 //
 
 conn.query('DROP TABLE IF EXISTS historyGroups');
-conn.query('CREATE TABLE historyGroups(categoryId INT NOT NULL, categoryValue FLOAT NOT NULL, historyId INT NOT NULL)');
+conn.query('CREATE TABLE historyGroups(categoryId INT NOT NULL, categoryValue FLOAT NOT NULL, historyId INT NOT NULL, FOREIGN KEY(historyId) REFERENCES history(id))');
 
 
 //
diff --git a/db/hscd.sql b/db/hscd.sql
index be8fa6a..e7916e4 100644
--- a/db/hscd.sql
+++ b/db/hscd.sql
@@ -50,7 +50,9 @@ CREATE TABLE `history` (
   `date` datetime NOT NULL,
   `reviewId` int(11) NOT NULL,
   `id` int(11) NOT NULL AUTO_INCREMENT,
-  PRIMARY KEY (`id`)
+  PRIMARY KEY (`id`),
+  KEY `reviewId` (`reviewId`),
+  CONSTRAINT `history_ibfk_1` FOREIGN KEY (`reviewId`) REFERENCES `reviews` (`id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
 /*!40101 SET character_set_client = @saved_cs_client */;
 
@@ -73,7 +75,9 @@ DROP TABLE IF EXISTS `historyGroups`;
 CREATE TABLE `historyGroups` (
   `categoryId` int(11) NOT NULL,
   `categoryValue` float NOT NULL,
-  `historyId` int(11) NOT NULL
+  `historyId` int(11) NOT NULL,
+  KEY `historyId` (`historyId`),
+  CONSTRAINT `historyGroups_ibfk_1` FOREIGN KEY (`historyId`) REFERENCES `history` (`id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
 /*!40101 SET character_set_client = @saved_cs_client */;
 
@@ -129,4 +133,4 @@ UNLOCK TABLES;
 /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
 /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
 
--- Dump completed on 2015-03-17 18:39:51
+-- Dump completed on 2015-03-26 13:31:52