diff --git a/Src/Asp.NetCore2/SqlSugar/Abstract/QueryableProvider/QueryableProvider.cs b/Src/Asp.NetCore2/SqlSugar/Abstract/QueryableProvider/QueryableProvider.cs
index 68b2701d5..f1f656065 100644
--- a/Src/Asp.NetCore2/SqlSugar/Abstract/QueryableProvider/QueryableProvider.cs
+++ b/Src/Asp.NetCore2/SqlSugar/Abstract/QueryableProvider/QueryableProvider.cs
@@ -1332,6 +1332,10 @@ namespace SqlSugar
         }
         public List<T> SetContext<ParameterT>(Expression<Func<T, object>> thisFiled, Expression<Func<object>> mappingFiled, ParameterT parameter) 
         {
+            if (parameter == null) 
+            {
+                return new List<T>();
+            }
             List<T> result = new List<T>();
             var entity = this.Context.EntityMaintenance.GetEntityInfo<ParameterT>();
             var queryableContext = this.Context.TempItems["Queryable_To_Context"] as MapperContext<ParameterT>;
@@ -1346,7 +1350,7 @@ namespace SqlSugar
                 pkName = ((mappingFiled as LambdaExpression).Body as MemberExpression).Member.Name;
             }
             var key = thisFiled.ToString() +typeof(ParameterT).FullName + typeof(T).FullName;
-            var ids = list.Select(it => it.GetType().GetProperty(pkName).GetValue(it)).ToArray();
+            var ids = list.Where(it=>it!=null).Select(it => it.GetType().GetProperty(pkName).GetValue(it)).Distinct().ToArray();
             if (queryableContext.TempChildLists == null)
                 queryableContext.TempChildLists = new Dictionary<string, object>();
             if (list != null &&  queryableContext.TempChildLists.ContainsKey(key))