Add demo

Src/Asp.Net/PgSqlTest/Demo/Demo2_Updateable.cs

@@ -77,6 +77,7 @@ namespace OrmTest
             var dt = new Dictionary<string, object>();
             dt.Add("id", 1);
             dt.Add("name", "abc");
+            dt.Add("CustomId", null);
             dt.Add("createTime", DateTime.Now);
             var dtList = new List<Dictionary<string, object>>();
             dtList.Add(dt);

Src/Asp.Net/PgSqlTest/Demo/Demo3_Insertable.cs

@@ -140,6 +140,12 @@ namespace OrmTest
            .AddSubList(it => it.TwoItem3)
            .ExecuteCommand();
 
+
+            var dict = new Dictionary<string, object>();
+            dict.Add("name", "1");
+            dict.Add("Price", 1);
+            dict.Add("CustomId", null);
+            db.Insertable(dict).AS("Order").ExecuteCommand();
             Console.WriteLine("#### Insertable End ####");
         }
     }