diff --git a/aula/schema.sql b/aula/schema.sql
index 5381c4a..8ab1069 100644
--- a/aula/schema.sql
+++ b/aula/schema.sql
@@ -5,7 +5,7 @@ CREATE TABLE IF NOT EXISTS users (
     first_name varchar(64) NOT NULL,
     last_name varchar(64) NOT NULL,
     password varchar(120) NOT NULL,
-    email varchar(64) NOT NULL,
+    email varchar(64) NOT NULL UNIQUE,
     address varchar(64) NOT NULL,
     role varchar(64) NOT NULL CHECK ( role in ('student', 'parent', 'teacher') )
 );