问题
I have db schema having tables like this below, i am trying to get the results using left join or normal join on these table using the below query. Somehow getting duplicate rows like as mentioned below.
Requests (table) RequestStage (table)
------------- ----------------
id RequestStageid
createdAt(datetime) name (values: RequestSubmitted,Inreview)
RequestTypeId
MasterSectionID
RequestStatusID
RequestStageID
id (FK)(localCodes)
MasterSections (table)
-------------------------
MasterSectionId
name (values: code1,Code2)
LocalCodes (table)
---------
Id
MasterSectionid
Name
description
...
...
I have inserted three rows into local code table at the same time three rows inserted into request table with requestStage as RequestSubmitted
Now i am trying to pull the rows which are having the status RequestSubmitted using below query. I should be able to get the 3 rows, instead of it i am getting 9 rows(i.e) I am getting 1 row three times.
if i apply distinct i am getting 3 rows but is there any other way to achieve this with out applying distinct
var results = (from re in _dbContext.Requests
join rt in _dbContext.RequestTypes on re.RequestTypeId equals rt.RequestTypeId
join rs in _dbContext.RequestStages on re.RequestStageId equals rs.RequestStageId
join ms in _dbContext.MasterSections on re.MasterSectionId equals ms.MasterSectionId
join lc in _dbContext.LocalCodes on ms.MasterSectionId equals lc.MasterSectionId
where rs.Name == "RequestSubmitted"
select new SectionResponse
{
Section = lc.Name,
Description = lc.Description,
CreatedBy = "",
Type = rt.Name.ToString(),
Status = rs.Name,
Age = (DateTime.Now.Date - re.CreatedAt.Date).TotalDays.ToString() + "Days"
}).ToList();
Another attempt:
(from re in _dbContext.Requests
join rt in _dbContext.RequestTypes on re.RequestTypeId equals rt.RequestTypeId into reqTypes
from x in reqTypes.DefaultIfEmpty()
join rs in _dbContext.RequestStages on re.RequestStageId equals rs.RequestStageId into reqStages
from y in reqStages.DefaultIfEmpty()
join ms in _dbContext.MasterSections on re.MasterSectionId equals ms.MasterSectionId into mstSections
from z in mstSections.DefaultIfEmpty()
join lc in _dbContext.LocalCodes on z.MasterSectionId equals lc.MasterSectionId into locCodes
from a in locCodes.DefaultIfEmpty()
where y.Name == "RequestSubmitted"
select new SectionResponse
{
Section = a.Name,
Description = a.Description,
CreatedBy = "",
Type = x.Name.ToString(),
Status = y.Name,
Age = (DateTime.Now.Date - re.CreatedAt.Date).TotalDays.ToString() + "Days"
}).ToList();
I am not sure where i am doing wrong in these queries, Could any one please suggest any idea on how to get only three rows. Also please let me know if you need any more information.
Many thanks
Domain models :
public class Request
{
public Guid RequestId { get; set; }
public string Description { get; set; }
public Guid DataId { get; set; }
public DateTime CreatedAt { get; set; }
public Guid MasterSectionId { get; set; }
public Guid RequestStatusId { get; set; }
public Guid RequestStageId { get; set; }
public Guid RequestTypeId { get; set; }
public MasterSection MasterSection { get; set; }
public RequestStatus Status { get; set; }
public RequestStage Stage { get; set; }
public RequestType RequestType { get; set; }
}
public class RequestStage
{
public Guid RequestStageId { get; set; }
public string Name { get; set; }
public ICollection<Request> Requests { get; set; }
}
public class MasterSection
{
public Guid MasterSectionId { get; set; }
public string Name { get; set; }
public ICollection<LocalCode> LocalCodes { get; set; }
public ICollection<Request> Requests { get; set; }
}
public class RequestStatus
{
public Guid RequestStatusId { get; set; }
public string Name { get; set; }
public ICollection<Request> Requests { get; set; }
}
public class LocalCode : IMasterObject
{
public Guid? Id { get; set; }
public string Name { get; set; }
public Guid MasterSectionId { get; set; }
public MasterSection MasterSection { get; set; }
}
回答1:
I tried using navigational properties and based on the description came up with below domain models. Please try this: (code is not tested though)
// Junction Table
public class Requests
{
[Key]
public int Id {get; set;}
public DateTime createdAt {get; set;}
[ForeginKey("RequestType")]
public int RequestTypeId {get; set;}
public virtual RequestType RequestType {get; set;}
[ForeginKey("MasterSections")]
public int MasterSectionID {get; set;}
public virtual MasterSections MasterSections {get; set;}
public int RequestStatusID {get; set;}
[ForeginKey("RequestStage")]
public int RequestStageID {get; set;}
public virtual RequestStage RequestStage {get; set;}
}
public class RequestStage
{
[Key]
public int RequestStageID {get; set;}
public string name {get; set;}
}
public class MasterSections
{
public int MasterSectionId {get; set;}
public string name {get; set;}
}
public class LocalCodes
{
[Key]
public int Id {get; set;}
[ForeginKey("MasterSections")]
public int MasterSectionId {get; set;}
public virtual MasterSections MasterSections {get; set;}
public string Description {get; set;}
public string name {get; set;}
}
If you want to use IQueryable then you can not calculate Age at the time of projection using .NET framework's DATE functions. You will need to use EF DATE related DBFunctions.
db.Requests.Include(r => r.RequestStage).Include(r => r.MasterSections)
.Where(r => r.RequestStage.name == "RequestSubmitted")
.Join(_dbContext.LocalCodes.Include(l => l.MasterSections), rqst => rqst.MasterSectionID, lc => lc.MasterSectionId,
(rt, lc) => new SectionResponse
{
Section = lc.Name,
Description = lc.Description,
CreatedBy = "",
Type = rt.Name.ToString(),
Status = rt.rs.Name,
/* Age property can not be done from within Queryable as .Date is not available in EF. If you want this, convert the query to enumerable and then project.*/
// Age = (DateTime.Now.Date - re.CreatedAt.Date).TotalDays.ToString() + "Days"
}).ToList();
By converting to Enumerable, you can calculate Age at the time projection like below:
db.Requests.Include(r => r.RequestStage).Include(r => r.MasterSections)
.Where(r => r.RequestStage.name == "RequestSubmitted")
.Join(_dbContext.LocalCodes.Include(l => l.MasterSections), rqst => rqst.MasterSectionID, lc => lc.MasterSectionId,
(rt, lc) => new {rt = rt, rs = rt.RequestStage, lc = lc, ms = lc.MasterSections}).AsEnumerable().
Select(anonType => new SectionResponse
{
Section = anonType.lc.Name,
Description = anonType.lc.Description,
CreatedBy = "",
Type = anonType.rt.Name.ToString(),
Status = anonType.rs.Name,
Age = (DateTime.Now.Date - anonType.rt.CreatedAt.Date).TotalDays.ToString() + "Days"
}).ToList();
Based on update to Request model, it can be achieved using below query:
db.Requests.Include(r => r.RequestStage).Include(r => r.RequestType).Include(r => r.LocalCodes.MasterSections)
.Where(r => r.RequestStage.name == "RequestSubmitted")
.Select(r => new {r = r, rt = r.RequestType, rs = rt.RequestStage, lc = r.lc, ms = r.lc.MasterSections}).AsEnumerable().
Select(anonType => new SectionResponse
{
Section = anonType.lc.Name,
Description = anonType.lc.Description,
CreatedBy = "",
Type = anonType.rt.Name.ToString(),
Status = anonType.rs.Name,
Age = $"{DateTime.Now.Date.Subtract(anonType.r.CreatedAt.Date).TotalDays} Days"
}).ToList();
来源：https://stackoverflow.com/questions/59259417/getting-duplicate-rows-for-each-row-using-linq-query