diff --git a/Service/Ammeter/EmeterEnergyChangeService.cs b/Service/Ammeter/EmeterEnergyChangeService.cs
index 5df5a23..c794f96 100644
--- a/Service/Ammeter/EmeterEnergyChangeService.cs
+++ b/Service/Ammeter/EmeterEnergyChangeService.cs
@@ -45,9 +45,10 @@ public class EmeterEnergyChangeService : BaseServices<EmeterEnergyChange>
     SELECT 
         d.`code`,
         d.`UploadTime`,
-        CASE 
-            WHEN d.`Count` = 1 THEN d.`MaxValue` - d.`PreviousMaxValue`
-            ELSE d.`MaxValue` - d.`MinValue`
+        CASE
+            WHEN d.`Count` > 1 THEN d.`MaxValue` - d.`MinValue`
+            WHEN d.`Count` = 1 AND d.`PreviousMaxValue` IS NOT NULL THEN d.`MaxValue` - d.`PreviousMaxValue`
+            ELSE 0
         END AS `DailyValue`
     FROM 
         previous_day_max d
@@ -65,6 +66,7 @@ ORDER BY
     `UploadTime`;
 
 
+
     ";
 
         List<EmeterEnergyChange> emeterEnergies = await _emeterEnergyChangeRep.SqlQueryable(sql);
diff --git a/Service/Ammeter/EmeterEnergyService.cs b/Service/Ammeter/EmeterEnergyService.cs
index 31b043b..134fbfa 100644
--- a/Service/Ammeter/EmeterEnergyService.cs
+++ b/Service/Ammeter/EmeterEnergyService.cs
@@ -50,8 +50,9 @@ public class EmeterEnergyService : BaseServices<EmeterEnergy>
         d.`code`,
         d.`UploadTime`,
         CASE 
-            WHEN d.`Count` = 1 THEN d.`MaxValue` - d.`PreviousMaxValue`
-            ELSE d.`MaxValue` - d.`MinValue`
+            WHEN d.`Count` > 1 THEN d.`MaxValue` - d.`MinValue`
+            WHEN d.`Count` = 1 AND d.`PreviousMaxValue` IS NOT NULL THEN d.`MaxValue` - d.`PreviousMaxValue`
+            ELSE 0
         END AS `DailyValue`
     FROM 
         previous_day_max d
@@ -69,6 +70,7 @@ ORDER BY
     `UploadTime`;
 
 
+
     ";
         List<EmeterEnergy> emeterEnergies = await this.BaseDal.SqlQueryable(sql);
         return emeterEnergies;