diff --git a/mnemo_cards_backend/lib/database/daos/statistics_dao.dart b/mnemo_cards_backend/lib/database/daos/statistics_dao.dart
index 4c76ee7..2901d9b 100644
--- a/mnemo_cards_backend/lib/database/daos/statistics_dao.dart
+++ b/mnemo_cards_backend/lib/database/daos/statistics_dao.dart
@@ -21,9 +21,13 @@ class StatisticsDao extends DatabaseAccessor<AppDatabase>
   }
 
   /// Получить сессию по sessionId (только активные)
-  Future<StudySession?> getSessionBySessionId(String sessionId) {
-    return (selectActive()..where((s) => s.sessionId.equals(sessionId)))
-        .getSingleOrNull();
+  Future<StudySession?> getSessionBySessionId(String sessionId) async {
+    final query = selectActive()
+      ..where((s) => s.sessionId.equals(sessionId))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить активные сессии пользователя (не завершенные и не удаленные)
diff --git a/mnemo_cards_backend/lib/database/daos/subscription_dao.dart b/mnemo_cards_backend/lib/database/daos/subscription_dao.dart
index 5b05241..c00a664 100644
--- a/mnemo_cards_backend/lib/database/daos/subscription_dao.dart
+++ b/mnemo_cards_backend/lib/database/daos/subscription_dao.dart
@@ -14,10 +14,13 @@ class SubscriptionDao extends DatabaseAccessor<AppDatabase>
   // ==================== SubscriptionPlans ====================
 
   /// Получить план подписки по ID
-  Future<SubscriptionPlan?> getPlanById(String id) {
-    return (select(
-      subscriptionPlans,
-    )..where((p) => p.id.equals(id))).getSingleOrNull();
+  Future<SubscriptionPlan?> getPlanById(String id) async {
+    final query = select(subscriptionPlans)
+      ..where((p) => p.id.equals(id))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить все планы подписки
@@ -41,22 +44,28 @@ class SubscriptionDao extends DatabaseAccessor<AppDatabase>
   // ==================== UserSubscriptions ====================
 
   /// Получить подписку пользователя
-  Future<UserSubscription?> getUserSubscription(String userId) {
-    return (select(userSubscriptions)
-          ..where((us) => us.userId.equals(userId))
-          ..orderBy([(us) => OrderingTerm.desc(us.finish)]))
-        .getSingleOrNull();
+  Future<UserSubscription?> getUserSubscription(String userId) async {
+    final query = select(userSubscriptions)
+      ..where((us) => us.userId.equals(userId))
+      ..orderBy([(us) => OrderingTerm.desc(us.finish)])
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить активную подписку пользователя
   Future<UserSubscription?> getActiveSubscription(String userId) async {
     final now = PgDateTime(DateTime.now());
-    return (select(userSubscriptions)
-          ..where((us) => us.userId.equals(userId))
-          ..where((us) => us.start.isSmallerThanValue(now))
-          ..where((us) => us.finish.isBiggerThanValue(now))
-          ..orderBy([(us) => OrderingTerm.desc(us.finish)]))
-        .getSingleOrNull();
+    final query = select(userSubscriptions)
+      ..where((us) => us.userId.equals(userId))
+      ..where((us) => us.start.isSmallerThanValue(now))
+      ..where((us) => us.finish.isBiggerThanValue(now))
+      ..orderBy([(us) => OrderingTerm.desc(us.finish)])
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Проверить, есть ли у пользователя активная подписка
diff --git a/mnemo_cards_backend/lib/database/daos/user_dao.dart b/mnemo_cards_backend/lib/database/daos/user_dao.dart
index 1b54863..0af4a70 100644
--- a/mnemo_cards_backend/lib/database/daos/user_dao.dart
+++ b/mnemo_cards_backend/lib/database/daos/user_dao.dart
@@ -15,8 +15,13 @@ class UserDao extends DatabaseAccessor<AppDatabase> with _$UserDaoMixin {
   // ==================== Users ====================
 
   /// Получить пользователя по ID
-  Future<User?> getUserById(String id) {
-    return (select(users)..where((u) => u.id.equals(id))).getSingleOrNull();
+  Future<User?> getUserById(String id) async {
+    final query = select(users)
+      ..where((u) => u.id.equals(id))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить пользователя с UserData
@@ -180,11 +185,13 @@ class UserDao extends DatabaseAccessor<AppDatabase> with _$UserDaoMixin {
   // ==================== Tokens ====================
 
   /// Получить токен по значению (только активные)
-  Future<Token?> getTokenByValue(String tokenValue) {
-    return (select(
-          tokens,
-        )..where((t) => t.token.equals(tokenValue) & t.isDeleted.equals(false)))
-        .getSingleOrNull();
+  Future<Token?> getTokenByValue(String tokenValue) async {
+    final query = select(tokens)
+      ..where((t) => t.token.equals(tokenValue) & t.isDeleted.equals(false))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить токен по externalUserId (только активные)
@@ -203,14 +210,17 @@ class UserDao extends DatabaseAccessor<AppDatabase> with _$UserDaoMixin {
   }
 
   /// Получить токен пользователя (только активные)
-  Future<Token?> getTokenByUserId(String userId) {
-    return (select(tokens)
-          ..where((t) => t.userId.equals(userId) & t.isDeleted.equals(false))
-          ..where(
-            (t) => t.expires.isBiggerThanValue(PgDateTime(DateTime.now())),
-          )
-          ..orderBy([(t) => OrderingTerm.desc(t.created)]))
-        .getSingleOrNull();
+  Future<Token?> getTokenByUserId(String userId) async {
+    final query = select(tokens)
+      ..where((t) => t.userId.equals(userId) & t.isDeleted.equals(false))
+      ..where(
+        (t) => t.expires.isBiggerThanValue(PgDateTime(DateTime.now())),
+      )
+      ..orderBy([(t) => OrderingTerm.desc(t.created)])
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Создать токен