diff --git a/api/tasks/batch_create_segment_to_index_task.py b/api/tasks/batch_create_segment_to_index_task.py
index 20335d9b9f..77feea47a2 100644
--- a/api/tasks/batch_create_segment_to_index_task.py
+++ b/api/tasks/batch_create_segment_to_index_task.py
@@ -8,7 +8,7 @@ import click
 import pandas as pd
 from celery import shared_task
 from graphon.model_runtime.entities.model_entities import ModelType
-from sqlalchemy import func
+from sqlalchemy import func, select
 
 from core.db.session_factory import session_factory
 from core.model_manager import ModelManager
@@ -140,10 +140,8 @@ def batch_create_segment_to_index_task(
             content = segment["content"]
             doc_id = str(uuid.uuid4())
             segment_hash = helper.generate_text_hash(content)
-            max_position = (
-                session.query(func.max(DocumentSegment.position))
-                .where(DocumentSegment.document_id == document_config["id"])
-                .scalar()
+            max_position = session.scalar(
+                select(func.max(DocumentSegment.position)).where(DocumentSegment.document_id == document_config["id"])
             )
             segment_document = DocumentSegment(
                 tenant_id=tenant_id,
diff --git a/api/tasks/delete_account_task.py b/api/tasks/delete_account_task.py
index ecf6f9cb39..55a99dde7a 100644
--- a/api/tasks/delete_account_task.py
+++ b/api/tasks/delete_account_task.py
@@ -1,6 +1,7 @@
 import logging
 
 from celery import shared_task
+from sqlalchemy import select
 
 from configs import dify_config
 from core.db.session_factory import session_factory
@@ -14,7 +15,7 @@ logger = logging.getLogger(__name__)
 @shared_task(queue="dataset")
 def delete_account_task(account_id):
     with session_factory.create_session() as session:
-        account = session.query(Account).where(Account.id == account_id).first()
+        account = session.scalar(select(Account).where(Account.id == account_id).limit(1))
         try:
             if dify_config.BILLING_ENABLED:
                 BillingService.delete_account(account_id)
diff --git a/api/tasks/duplicate_document_indexing_task.py b/api/tasks/duplicate_document_indexing_task.py
index 13c651753f..6bc58bdf9c 100644
--- a/api/tasks/duplicate_document_indexing_task.py
+++ b/api/tasks/duplicate_document_indexing_task.py
@@ -82,7 +82,7 @@ def _duplicate_document_indexing_task(dataset_id: str, document_ids: Sequence[st
 
     with session_factory.create_session() as session:
         try:
-            dataset = session.query(Dataset).where(Dataset.id == dataset_id).first()
+            dataset = session.scalar(select(Dataset).where(Dataset.id == dataset_id).limit(1))
             if dataset is None:
                 logger.info(click.style(f"Dataset not found: {dataset_id}", fg="red"))
                 return
diff --git a/api/tests/unit_tests/tasks/test_delete_account_task.py b/api/tests/unit_tests/tasks/test_delete_account_task.py
index 8a12a4a169..f949c13158 100644
--- a/api/tests/unit_tests/tasks/test_delete_account_task.py
+++ b/api/tests/unit_tests/tasks/test_delete_account_task.py
@@ -26,9 +26,6 @@ def mock_db_session():
         cm.__exit__.return_value = None
         mock_sf.create_session.return_value = cm
 
-        query = MagicMock()
-        session.query.return_value = query
-        query.where.return_value = query
         yield session
 
 
@@ -49,12 +46,12 @@ def mock_deps():
 
 def _set_account_found(mock_db_session, email: str = "user@example.com"):
     account = SimpleNamespace(email=email)
-    mock_db_session.query.return_value.where.return_value.first.return_value = account
+    mock_db_session.scalar.return_value = account
     return account
 
 
 def _set_account_missing(mock_db_session):
-    mock_db_session.query.return_value.where.return_value.first.return_value = None
+    mock_db_session.scalar.return_value = None
 
 
 class TestDeleteAccountTask: