LINQ to Entities 不支持指定的类型成员“Date”。

解决方案一：等号两边都转换格式再比较

System.Data.Entity.DbFunctions.TruncateTime(airHourly.Date)

dateHour = dateHour.Date;

解决方案二：等号改成区间

DateTime dateHour = DateTime.Now.Date;
DateTime dateHourEnd = DateTime.Now.Date.AddDays(1);

airHourly.Date >=dateHour &&airHourly.Date<dateHourEnd

private JsonResult StreetStationHourlyData(PageModel pageInfo, DateTime dateHour, string[] stations)//, string[] param, string[] stationTypeArray
{
    ResultModel result = new ResultModel();
    if (pageInfo.Page <= 0)
    {
        pageInfo.Page = 1;
    }
    if (pageInfo.Rows <= 0)
    {
        pageInfo.Rows = 20;
    }
    //int[] stationIntArray = Array.ConvertAll<string, int>(stations, s => int.Parse(s));
    dateHour = dateHour.Date;
    var data = from airHourly in dbq.T_AirStreetDataHourly2
               join station in dbq.T_AirStreetStation2
               on airHourly.StationID equals station.StationID.ToString()
               where airHourly.StationID != null && System.Data.Entity.DbFunctions.TruncateTime(airHourly.Date) == dateHour && stations.Contains(station.StationID.ToString()) //&& stationTypeArray.Contains(station.SeatType.ToString())
               orderby airHourly.StationID, airHourly.Date.Hour
               select new { station.StationName, airHourly.StationID, airHourly.Date, airHourly.O3, airHourly.PM10, airHourly.PM25, Hour=airHourly.Date.Hour, station.Hierarchy, station.SeatType, station.PointNature, station.IsStreet };
    //排序
    if (pageInfo.Order != null && pageInfo.Sort != null)
    {
        bool isAsc = pageInfo.Order == "asc";
        data = data.OrderBy(new[] { pageInfo.Sort }, new[] { isAsc });
    }
 
    result.rows = data.Skip((pageInfo.Page - 1) * pageInfo.Rows).Take(pageInfo.Rows).ToList();
    result.total = data.Count();
    result.success = true;
    return Json(result, JsonRequestBehavior.AllowGet);
 
}