diff --git a/README.md b/README.md
index 2a864d9..838a9e2 100644
--- a/README.md
+++ b/README.md
@@ -28,14 +28,14 @@ Connect to the database as user *kosync* (with psql) and create the database tab
 ```sql
 CREATE TABLE users (
   id BIGSERIAL PRIMARY KEY,
-  username TEXT NOT NULL,
+  username TEXT UNIQUE NOT NULL,
   password TEXT
 );
 
 CREATE TABLE progresses (
   id BIGSERIAL PRIMARY KEY,
   user_id BIGINT,
-  document TEXT UNIQUE NOT NULL,
+  document TEXT NOT NULL,
   progress TEXT NOT NULL,
   percentage REAL NOT NULL,
   device TEXT NOT NULL,
@@ -45,4 +45,4 @@ CREATE TABLE progresses (
      REFERENCES users(id) ON DELETE CASCADE,
   UNIQUE (user_id, document)
 );
-```
\ No newline at end of file
+```