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DateTime a = objectSearch["specificDay"];
DateTime firstDateTime = DateTime.parse(DateTime(a.year, a.month, a.day).toString() + "Z");
DateTime secondDateTime = DateTime.parse(DateTime(a.year, a.month, a.day + 1).toString() + "Z");
mainQuery.whereGreaterThanOrEqualsTo("checkUpDate", firstDateTime);
mainQuery.whereLessThan("checkUpDate", secondDateTime);