asp.net - WHERE 的 stimulsoft 问题

Question

我在 stimulsoft 中有一份报告，它可以很好地处理这个查询

SELECT Car.IDCar, Car.NameCar, Car.Code, Car.DriverName, Car.IsTruck,
  CarData.IDCarData, CarData.Start, CarData.End, CarData.Total,
  CarData.Distance, CarData.Weight, CarData.Controller, CarData.Scope,
  CarData.Description, CarData.Date
FROM Car LEFT JOIN
  CarData ON Car.IDCar = CarData.CarID
WHERE CarData.Date= '20150515'

但是当我想像下面这样使用它时，它不会返回任何数据

SELECT Car.IDCar, Car.NameCar, Car.Code, Car.DriverName, Car.IsTruck,
  CarData.IDCarData, CarData.Start, CarData.End, CarData.Total,
  CarData.Distance, CarData.Weight, CarData.Controller, CarData.Scope,
  CarData.Description, CarData.Date
FROM Car LEFT JOIN
  CarData ON Car.IDCar = CarData.CarID
WHERE CarData.Date= '20150515' and Car.IsTruck='yes'

不得不提的是我的数据是波斯语的，所以原来的查询是 >

WHERE CarData.Date= '20150515' and Car.IsTruck='بلی'