diff --git a/bd/tables/response.py b/bd/tables/response.py
index 41e4daa..e410a84 100644
--- a/bd/tables/response.py
+++ b/bd/tables/response.py
@@ -11,7 +11,7 @@ class Response(Base):
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
     poll_id = Column(UUID(as_uuid=True), ForeignKey("polls.id", ondelete="CASCADE"), nullable=False)
-    user_id = Column(UUID(as_uuid=True), nullable=True)
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=True)
     # Снимок группы и организации пользователя на момент прохождения
     group_id = Column(UUID(as_uuid=True), nullable=True)
     organization_id = Column(UUID(as_uuid=True), nullable=True)
diff --git a/route/init_data_base.py b/route/init_data_base.py
index 4e553a2..5542382 100644
--- a/route/init_data_base.py
+++ b/route/init_data_base.py
@@ -70,6 +70,30 @@ async def create_tables():
         raise HTTPException(status_code=500, detail=str(e))
 
 
+@router.post("/db/migrate-cascade-user", dependencies=[Depends(require_admin_key)])
+async def migrate_cascade_user():
+    """Добавляет FK responses.user_id → users.id ON DELETE CASCADE, если ещё не существует."""
+    engine = make_engine()
+    try:
+        with engine.connect() as conn:
+            conn.execute(text("""
+                DO $$ BEGIN
+                    IF NOT EXISTS (
+                        SELECT 1 FROM pg_constraint
+                        WHERE conname = 'responses_user_id_fkey'
+                    ) THEN
+                        ALTER TABLE responses
+                        ADD CONSTRAINT responses_user_id_fkey
+                        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
+                    END IF;
+                END $$;
+            """))
+            conn.commit()
+        return {"status": "ok", "detail": "FK responses.user_id → users(id) ON DELETE CASCADE ensured"}
+    except SQLAlchemyError as e:
+        raise HTTPException(status_code=500, detail=str(e))
+
+
 @router.post("/db/migrate-users", dependencies=[Depends(require_admin_key)])
 async def migrate_users():
     """Добавляет колонки username и hashed_password в таблицу users, если они ещё не существуют."""