Update QueryobjectBug

Src/Asp.Net/MySqlTest/Demos/1_Query.cs

@@ -216,6 +216,7 @@ namespace OrmTest.Demo
             var date = db.Queryable<Student>().Where(it => it.CreateTime.Value.Date ==DateTime.Now.Date).ToList();
             var isAny2 = db.Queryable<Student>().Any(it => it.Id == -1);
             var getListByRename = db.Queryable<School>().AS("Student").ToList();
+            var asCount = db.Queryable<object>().AS("student").Count();
             var in1 = db.Queryable<Student>().In(it => it.Id, new int[] { 1, 2, 3 }).ToList();
             var in2 = db.Queryable<Student>().In(new int[] { 1, 2, 3 }).ToList();
             int[] array = new int[] { 1, 2 };

Src/Asp.Net/SqlSugar/Abstract/SqlBuilderProvider/QueryBuilder.cs

@@ -400,7 +400,10 @@ namespace SqlSugar
                 reval = this.SelectValue.ObjToString();
                 this.SelectCacheKey = reval;
             }
-
+            if (reval.IsNullOrEmpty())
+            {
+                reval = "*";
+            }
             return reval;
         }
         public virtual string GetWhereValueString