我的数据库中有一个包含四列的表：
string: year
string: weeknr
int: number
在其他表中，我将这些列组合成yywwnnn作为字符串。
数字列是标识列。
现在我想从要与上述表连接的表中检索一些记录。
就像是：
from R in db.Requests
join RN in db.RequestNumbers on R.RequestNumber equals (RN.Year + RN.Weeknr + RN.Number)
但当然 RN.Number 是一个整数，我需要它是一个 3 位数的字符串。
so:
16 07 1 ==> 1607001
16 07 10 ==> 1607010
16 07 100 ==> 1607100
我已经尝试过这个：
from R in db.Requests
join RN in db.RequestNumbers on R.RequestNumber equals (RN.Year + RN.Weeknr + (RN.Number.toString().PadLeft(3,char.Parse("0")))
但 PadLeft 不被识别。
对此还有其他解决方案吗？
[编辑]
这是完整的方法：
public List<RequestList> getMyRequests(string userID)
{
var result = (from R in db.Requests
join MT in db.MainTorsList on R.Category equals MT.MainTorsListID into MTL
from MT in MTL.DefaultIfEmpty()
join ST in db.SubTorsList on R.RequestType equals ST.SubTorsListID into STL
from ST in STL.DefaultIfEmpty()
join S in db.StatusList on R.RequestStatus equals S.StatusListID into SL
from S in SL.DefaultIfEmpty()
join RN in db.RequestNumber on R.RequestNumber equals RN.Year + RN.Week + (RN.Number.ToString().PadLeft(3, char.Parse("0"))) into RNL
from RN in RNL.DefaultIfEmpty()
where R.CreatedBy == userID && RN.Removed == false
select new
{
RequestID = R.RequestID,
RequestDate = R.CreatedOn,
RequestNumber = R.RequestNumber,
Category = MT.Name,
RequestType = ST.Name,
Description = R.RequestDescription,
Status = S.Name,
Options = ""
}
);
List<RequestList> requests = (List<RequestList>)result.ToList().ToNonAnonymousList(typeof(RequestList));
return requests;
}
错误信息：
Additional information: LINQ to Entities does not recognize the method 'System.String PadLeft(Int32, Char)' method, and this method cannot be translated into a store expression.
