diff --git a/init/sql/000-init.sql b/init/sql/000-init.sql
index bdf70419c88b2bad607411a29d1fa09dcb949af8..7db793e65829e5b96cabfec711aa19e3a5414e07 100644
--- a/init/sql/000-init.sql
+++ b/init/sql/000-init.sql
@@ -40,7 +40,7 @@ CREATE TABLE relations (
 );
 
 CREATE TABLE transactions (
-    id                      CHAR(12) NOT NULL,
+    id                      CHAR(12) NOT NULL PRIMARY KEY,
     user_id                 INTEGER NOT NULL
                             CONSTRAINT transaction_user_id REFERENCES "users",
     combination_id          INTEGER NULL