diff --git a/migrations.sql b/migrations.sql
index b5fd81c..1ffe7e5 100644
--- a/migrations.sql
+++ b/migrations.sql
@@ -70,7 +70,12 @@ CREATE TABLE labels(
 );
 
 CREATE TABLE card_labels (
+    id BIGSERIAL PRIMARY KEY,
     user_uuid VARCHAR(36) NOT NULL,
     label_uuid VARCHAR(36) NOT NULL,
     merch_uuid VARCHAR(36) NOT NULL
 );
+
+ALTER TABLE card_labels
+    ADD CONSTRAINT card_labels_unique_user_label_merch
+        UNIQUE (user_uuid, label_uuid, merch_uuid);
\ No newline at end of file