修复统计数据 API 中的数据库查询方法，优化性能和准确性

src/webui/routers/statistics.py

@@ -134,7 +134,7 @@ async def _get_summary_statistics(start_time: datetime, end_time: datetime) -> S
             func.sum(col(ModelUsage.total_tokens)).label("total_tokens"),
             func.avg(col(ModelUsage.time_cost)).label("avg_response_time"),
         ).where(col(ModelUsage.timestamp) >= start_time, col(ModelUsage.timestamp) <= end_time)
-        result = session.execute(statement).first()
+        result = session.exec(statement).first()
 
     if result:
         total_requests, total_cost, total_tokens, avg_response_time = result
@@ -151,7 +151,7 @@ async def _get_summary_statistics(start_time: datetime, end_time: datetime) -> S
                 col(OnlineTime.end_timestamp) >= start_time,
             )
         )
-        online_records = session.execute(statement).scalars().all()
+        online_records = session.exec(statement).all()
 
         for record in online_records:
             start = max(record.start_timestamp, start_time)
@@ -165,7 +165,7 @@ async def _get_summary_statistics(start_time: datetime, end_time: datetime) -> S
             col(Messages.timestamp) >= start_time,
             col(Messages.timestamp) <= end_time,
         )
-        total_messages = session.execute(statement).scalar()
+        total_messages = session.exec(statement).one()
     summary.total_messages = int(total_messages or 0)
 
     # 统计回复数量
@@ -175,7 +175,7 @@ async def _get_summary_statistics(start_time: datetime, end_time: datetime) -> S
             col(Messages.timestamp) <= end_time,
             col(Messages.reply_to).is_not(None),
         )
-        total_replies = session.execute(statement).scalar()
+        total_replies = session.exec(statement).one()
     summary.total_replies = int(total_replies or 0)
 
     # 计算派生指标
@@ -198,7 +198,7 @@ async def _get_model_statistics(start_time: datetime) -> list[ModelStatistics]:
     )
 
     with get_db_session() as session:
-        rows = session.execute(statement).all()
+        rows = session.exec(statement).all()
 
         aggregates: dict[str, dict[str, float | int]] = {}
         for record in rows:
@@ -257,7 +257,7 @@ async def _get_hourly_statistics(start_time: datetime, end_time: datetime) -> li
     )
 
     with get_db_session() as session:
-        rows = session.execute(statement).all()
+        rows = session.exec(statement).all()
 
     # 转换为字典以快速查找
     data_dict = {row[0]: row for row in rows}
@@ -300,7 +300,7 @@ async def _get_daily_statistics(start_time: datetime, end_time: datetime) -> lis
     )
 
     with get_db_session() as session:
-        rows = session.execute(statement).all()
+        rows = session.exec(statement).all()
 
     # 转换为字典
     data_dict = {row[0]: row for row in rows}
@@ -331,7 +331,7 @@ async def _get_recent_activity(limit: int = 10) -> list[dict[str, Any]]:
     """获取最近活动"""
     with get_db_session() as session:
         statement = select(ModelUsage).order_by(desc(col(ModelUsage.timestamp))).limit(limit)
-        records = session.execute(statement).scalars().all()
+        records = session.exec(statement).all()
 
         activities = []
         for record in records: