diff --git a/vnpy/app/data_recorder/ui/widget.py b/vnpy/app/data_recorder/ui/widget.py
index 44809baa..553a9d37 100644
--- a/vnpy/app/data_recorder/ui/widget.py
+++ b/vnpy/app/data_recorder/ui/widget.py
@@ -3,7 +3,7 @@ from datetime import datetime
 
 from vnpy.event import Event, EventEngine
 from vnpy.trader.engine import MainEngine
-from vnpy.trader.ui import QtCore, QtGui, QtWidgets
+from vnpy.trader.ui import QtCore, QtWidgets
 from vnpy.trader.event import EVENT_CONTRACT
 
 from ..engine import (
diff --git a/vnpy/trader/database/database_sql.py b/vnpy/trader/database/database_sql.py
index 7452e467..41e54856 100644
--- a/vnpy/trader/database/database_sql.py
+++ b/vnpy/trader/database/database_sql.py
@@ -334,11 +334,11 @@ class SqlManager(BaseDatabaseManager):
         s = (
             self.class_bar.select()
             .where(
-                (self.class_bar.symbol == symbol) &
-                (self.class_bar.exchange == exchange.value) &
-                (self.class_bar.interval == interval.value) &
-                (self.class_bar.datetime >= start) &
-                (self.class_bar.datetime <= end)
+                (self.class_bar.symbol == symbol) 
+                & (self.class_bar.exchange == exchange.value) 
+                & (self.class_bar.interval == interval.value) 
+                & (self.class_bar.datetime >= start) 
+                & (self.class_bar.datetime <= end)
             )
             .order_by(self.class_bar.datetime)
         )
@@ -351,10 +351,10 @@ class SqlManager(BaseDatabaseManager):
         s = (
             self.class_tick.select()
             .where(
-                (self.class_tick.symbol == symbol) &
-                (self.class_tick.exchange == exchange.value) &
-                (self.class_tick.datetime >= start) &
-                (self.class_tick.datetime <= end)
+                (self.class_tick.symbol == symbol) 
+                & (self.class_tick.exchange == exchange.value) 
+                & (self.class_tick.datetime >= start) 
+                & (self.class_tick.datetime <= end)
             )
             .order_by(self.class_tick.datetime)
         )
@@ -376,9 +376,9 @@ class SqlManager(BaseDatabaseManager):
         s = (
             self.class_bar.select()
             .where(
-                (self.class_bar.symbol == symbol) &
-                (self.class_bar.exchange == exchange.value) &
-                (self.class_bar.interval == interval.value)
+                (self.class_bar.symbol == symbol) 
+                & (self.class_bar.exchange == exchange.value) 
+                & (self.class_bar.interval == interval.value)
             )
             .order_by(self.class_bar.datetime.desc())
             .first()
@@ -393,8 +393,8 @@ class SqlManager(BaseDatabaseManager):
         s = (
             self.class_tick.select()
             .where(
-                (self.class_tick.symbol == symbol) &
-                (self.class_tick.exchange == exchange.value)
+                (self.class_tick.symbol == symbol) 
+                & (self.class_tick.exchange == exchange.value)
             )
             .order_by(self.class_tick.datetime.desc())
             .first()