generated SQL Query changes based on different selection in Linq - c#

I am converting an SQL query to LINQ. It has multiple inner, left and right joins. I'm checking the generated SQL from LINQ in every step. But the problem is based on the selection the generated sql query changes.
Below my Linq
var a = from freight in billingEntity.FreightCharges.AsNoTracking()
join service in billingEntity.ServiceTypes.AsNoTracking()
on freight.ServiceTypeId equals service.Id
join transport in billingEntity.TransportationTypes.AsNoTracking()
on freight.TransportationTypeId equals transport.Id
join division in billingEntity.DivisionDetails.AsNoTracking()
on freight.OriginId equals division.OriginID
join mail in billingEntity.Mailclasses.AsNoTracking()
on freight.MailClassId equals mail.MailClassId
into mailClassFreight
from mail in mailClassFreight.DefaultIfEmpty()
join process in billingEntity.ProcessingCategories.AsNoTracking()
on freight.ProcessingcategoryId equals process.ProcessingCategoryId
into processFreight
from processCategory in processFreight.DefaultIfEmpty()
select mail;
string v = a.ToString();
This generated SQL as
SELECT
[Extent3].[MailClassId] AS [MailClassId],
[Extent3].[MailClassName] AS [MailClassName],
[Extent3].[CreatedDate] AS [CreatedDate]
FROM [dbo].[FreightCharges] AS [Extent1]
INNER JOIN [dbo].[DivisionDetails] AS [Extent2] ON [Extent1].[OriginId] = [Extent2].[OriginID]
LEFT OUTER JOIN [dbo].[Mailclass] AS [Extent3] ON [Extent1].[MailClassId] = [Extent3].[MailClassId]
WHERE ([Extent1].[ServiceTypeId] IS NOT NULL) AND ([Extent1].[TransportationTypeId] IS NOT NULL)
Where I can see the dbo.ProcessingCategory is missing in the join.
If I do select processCategory the SQL generates with missing dbo.MailClass.
The SQL query I am trying to convert to LINQ is below
select * from
dbo.FreightCharges as fc
inner join dbo.ServiceType as st
on fc.ServiceTypeId = st.Id
inner join dbo.TransportationTypes as tt
on fc.TransportationTypeId = tt.Id
inner join dbo.DivisionDetails as dd
on fc.OriginId = dd.OriginId
left join dbo.Mailclass as mc
on fc.MailClassId = mc.MailClassId
left join dbo.ProcessingCategory as pc
on fc.ProcessingcategoryId = pc.ProcessingCategoryId
right join dbo.ContentTitle as ct
on fc.ContentTitleId = ct.ContentTitleId
inner join dbo.AccountDetails as ac
on ct.AccountId = ac.AccountId
where
fc.EffectiveThruDate >= '9999-12-31'
or
fc.EffectiveThruDate is null


You can change your query joins to left joins like this.
select * from
dbo.ContentTitle ct
inner join dbo.AccountDetails as ac
on ct.AccountId = ac.AccountId
left join dbo.FreightCharges as fc
on fc.ContentTitleId = ct.ContentTitleId and fc.EffectiveThruDate >= '9999-12-31'
left join dbo.ServiceType as st
on fc.ServiceTypeId = st.Id
left join dbo.TransportationTypes as tt
on fc.TransportationTypeId = tt.Id
left join dbo.DivisionDetails as dd
on fc.OriginId = dd.OriginId
left join dbo.Mailclass as mc
on fc.MailClassId = mc.MailClassId
left join dbo.ProcessingCategory as pc
on fc.ProcessingcategoryId = pc.ProcessingCategoryId
Linq equivalent
from ct in ContentTitles
join ac in AccountDetails on ct.AccountId equals ac.AccountId
join fc in FreightCharges on ct.ContentTitleId equals fc.ContentTitleId into lfc
from flfc in lfc.Where(f => f.EffectiveThruDate >= new DateTime(9999,12,31)).DefaultIfEmpty()
join st in ServiceTypes on flfc.ServiceTypeId equals st.Id into lst
from flst in lst.DefaultIfEmpty()
join tt in TransportationTypes on flfc.TransportationTypeId equals tt.Id into ltt
from fltt in ltt.DefaultIfEmpty()
join dd in DivisionDetails on flfc.OriginId equals dd.OriginId into ldd
from fldd in ldd.DefaultIfEmpty()
join mc in Mailclasses on flfc.MailClassId equals mc.MailClassId into lmc
from flmc in lst.DefaultIfEmpty()
join pc in ProcessingCategories on flfc.ProcessingcategoryId equals pc.ProcessingCategoryId into lpc
from flpc in lst.DefaultIfEmpty()
select new {ct, ac, lfc, lst ,ltt, ldd, lmc, lpc}

Related

How can I write this query in LINQ

I have this query
SELECT t.NomeTipo, sum(v.QtdProduto)
FROM [dbo].[Vendas] AS V
RIGHT JOIN [dbo].[Produtos] AS P ON V.IdProduto = P.IdProduto
INNER JOIN [dbo].[Tipos] AS T ON P.IdTipo = T.IdTipo
group by t.NomeTipo
order by t.NomeTipo
I have tried this
var queryTipos = from vendas in repositorioVendas.Vendas
join produtos in repositorioProduto.Produtos.DefaultIfEmpty()
on vendas.IdProduto equals produtos.IdProduto
join tipos in repositorioTipo.Tipos
on produtos.IdTipo equals tipos.IdTipo
group vendas by new { tipos.NomeTipo, vendas.QtdProduto }
into novoGrupo
select new
{
NomeTipo = novoGrupo.Key.NomeTipo,
QtdProduto = novoGrupo.Sum(x => x.QtdProduto)
};
With this query I got only two results, but when I run straight from the database I get something like this:
Bebidas 16
Bolos 14
Frios 16
Pães 21

The trick is to realize that you can rewrite your query with a left join instead of a right join by swapping the order of the first two tables and that Linq doesn't have a way to really handle right joins. Also you're grouping was wrong.
var queryTipos = from produtos in repositorioProduto.Produtos
join vendas_pj in repositorioVendas.Vendas
on vendas_pj.IdProduto equals produtos.IdProduto into joined
from vendas in joined.DefaultIfEmpty()
join tipos in repositorioTipo.Tipos
on produtos.IdTipo equals tipos.IdTipo
group vendas by tipos.NomeTipo
into novoGrupo
select new
{
NomeTipo = novoGrupo.Key,
QtdProduto = novoGrupo.Sum(x => x.QtdProduto)
};
Basically a Left join in SQL
From TableA
Left Join TableB
On TableA.ID = TableB.ID
is done in Linq like this
from a in repo.TableA
join b_pj in repo.TableB
on a.ID equals b_pj.ID into joined
from b in joined.DefaultIfEmpty()

How to use left outer join in Linq

I have a SQL statement
SELECT
cci.[ID], cci.[OwnerFirstName], cci.[OwnerLastName], cci.[CompanyName],
cci.[AddressLine1], cci.[AddressLine2], cci.[AddressLine3], cci.[AddressLine4],
cci.[AddressLine5], cci.[AddressCity], sp1.[Abbreviation] AS [StateAbbreviation],
sp2.[Abbreviation] AS [ProvinceAbbreviation], cci.[AddressPostalCode],
cr1.[Name] AS [CountryName], cr2.[Name] AS [RegionName], cci.[AddressNote],
cci.[Phone1], cci.[Phone2], cci.[Phone3], cci.[Phone4], cci.[Phone5],
cci.[Fax1], cci.[Fax2], cci.[Fax3], cci.[Fax4], cci.[Fax5], cci.[Email1],
cci.[Email2], cci.[Email3], cci.[Email4], cci.[Email5], cci.[CompanyWebSite],
ci.[EIN], ci.[SSN], cli.[LegalName], cli.[LegalAddressLine1], cli.[LegalAddressLine2],
cli.[LegalAddressLine3], cli.[LegalAddressLine4], cli.[LegalAddressLine5],
cli.[LegalAddressCity], sp3.[Abbreviation] AS [LegalAddressStateAbbreviation],
sp4.[Abbreviation] AS [LegalAddressProvinceAbbreviation], cli.[LegalAddressPostalCode],
cr3.[Name] AS [LegalAddressCountryName], cr4.[Name] AS [LegalAddressRegionName],
cli.[LegalAddressNote], cri.[FirstMonthFiscalYear], cri.[FirstMonthIncomeTaxYear],
CONCAT(CONCAT(CONCAT(itfl.[TaxForm], ' - ('),itfl.[Description]), ')') AS [TaxForm],
c.[CryptoPassPhrase], c.[CryptoVector], c.[CryptoMinSALTLen],
c.[CryptoMaxSALTLen], c.[CryptoKeySize], c.[CryptoHash], c.[CryptoSALT],
c.[CryptoIterations], ga.[AccountCode], ga.[UseAnalytics],
CONCAT(CONCAT(CONCAT(CONCAT(e1.[LastName], ', '), e1.[FirstName]), ' '), e1.[MiddleName]) AS [CreatedBy],
sd.[CreatedByID], sd.[CreatedDateTime],
CONCAT(CONCAT(CONCAT(CONCAT(e2.[LastName], ', '), e2.[FirstName]), ' '), e2.[MiddleName]) AS [ModifiedBy],
sd.[ModifiedByID], sd.[ModifiedDateTime], sd.[SiteDescription],
s.[SMTPServer], s.[SMTPUserName], s.[SMTPUserName], s.[SMTPPassword],
s.[SMTP_TO], s.[SMTP_CC], s.[SMTP_BCC], s.[SMTPEncoding]
FROM [settings].[CompanyContactInformation] cci
LEFT OUTER JOIN [settings].[CompanyIdentification] ci ON cci.[ID] = ci.[SiteID]
LEFT OUTER JOIN [settings].[CompanyLegalInformation] cli ON cci.[ID] = cli.[ID]
LEFT OUTER JOIN [settings].[CompanyReportInformation] cri ON cci.[ID] = cri.[SiteID]
LEFT OUTER JOIN [settings].[Cryptography] c ON cci.[ID] = c.[SiteID]
LEFT OUTER JOIN [settings].[GoogleAnalytics] ga ON cci.[ID] = ga.[SiteID]
LEFT OUTER JOIN [settings].[IncomeTaxFormList] itfl ON cri.[TaxFormID] = itfl.[ID]
LEFT OUTER JOIN [settings].[SiteDetails] sd ON cci.[ID] = sd.[SiteID]
LEFT OUTER JOIN [settings].[SMTP] s ON cci.[ID] = s.[SiteID]
LEFT OUTER JOIN [dbo].[Employee] e1 ON sd.[CreatedByID] = e1.[ID]
LEFT OUTER JOIN [dbo].[Employee] e2 ON sd.[ModifiedByID] = e2.[ID]
LEFT OUTER JOIN [dbo].[CountryOrRegion] cr1 ON cci.[AddressCountryID] = cr1.[ID]
LEFT OUTER JOIN [dbo].[CountryOrRegion] cr2 ON cci.[AddressRegionID] = cr2.[ID]
LEFT OUTER JOIN [dbo].[CountryOrRegion] cr3 ON cli.[LegalAddressCountryID] = cr3.[ID]
LEFT OUTER JOIN [dbo].[CountryOrRegion] cr4 ON cli.[LegalAddressRegionID] = cr4.[ID]
LEFT OUTER JOIN [dbo].[StateOrProvince] sp1 ON cci.[AddressStateID] = sp1.[ID]
LEFT OUTER JOIN [dbo].[StateOrProvince] sp2 ON cci.[AddressProvinceID] = sp2.[ID]
LEFT OUTER JOIN [dbo].[StateOrProvince] sp3 ON cli.[LegalAddressStateID] = sp3.[ID]
LEFT OUTER JOIN [dbo].[StateOrProvince] sp4 ON cli.[LegalAddressProvinceID] = sp4.[ID]
So far I have the following LINQ statement in LinqPad:
var q = (
from cci in CompanyContactInformation
join sp1 in StateOrProvince on cci.AddressStateID equals sp1.ID into t1
from rt1 in t.DefaultIfEmpty()
select new {
cci.ID, cci.OwnerFirstName, cci.OwnerLastName, cci.CompanyName,
cci.AddressLine1, cci.AddressLine2,cci.AddressLine3,
cci.AddressLine4, cci.AddressLine5, cci.AddressCity,
StateAbbreviation = sp1.Abbreviation
}).ToList();
q.Dump();
And I am getting the following error:
'LINQPad.User.StateOrProvince' is a 'type' but is used like a 'variable'
The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'GroupJoin'.
What am I doing wrong here?

Solved it after pulling my hair out. Had to pluralize some of the tables. Here is the proper LINQ statement:
var q = (
from cci in CompanyContactInformation
join ci in CompanyIdentifications on cci.ID equals ci.SiteID into t1 from rt1 in t1.DefaultIfEmpty()
join cli in CompanyLegalInformation on cci.ID equals cli.ID into t2 from rt2 in t2.DefaultIfEmpty()
join cri in CompanyReportInformation on cci.ID equals cri.SiteID into t3 from rt3 in t3.DefaultIfEmpty()
join c in Cryptographies on cci.ID equals c.SiteID into t4 from rt4 in t4.DefaultIfEmpty()
join ga in GoogleAnalytics on cci.ID equals ga.SiteID into t5 from rt5 in t5.DefaultIfEmpty()
join itfl in IncomeTaxFormLists on rt3.TaxFormID equals itfl.ID into t6 from rt6 in t6.DefaultIfEmpty()
join sd in SiteDetails on cci.ID equals sd.SiteID into t7 from rt7 in t7.DefaultIfEmpty()
join s in SMTPs on cci.ID equals s.SiteID into t8 from rt8 in t8.DefaultIfEmpty()
join e1 in Employees on rt7.CreatedByID equals e1.ID into t9 from rt9 in t9.DefaultIfEmpty()
join e2 in Employees on rt7.ModifiedByID equals e2.ID into t10 from rt10 in t10.DefaultIfEmpty()
join cr1 in CountryOrRegions on cci.AddressCountryID equals cr1.ID into t11 from rt11 in t11.DefaultIfEmpty()
join cr2 in CountryOrRegions on cci.AddressRegionID equals cr2.ID into t12 from rt12 in t12.DefaultIfEmpty()
join cr3 in CountryOrRegions on rt2.LegalAddressCountryID equals cr3.ID into t13 from rt13 in t13.DefaultIfEmpty()
join cr4 in CountryOrRegions on rt2.LegalAddressRegionID equals cr4.ID into t14 from rt14 in t14.DefaultIfEmpty()
join sp1 in StateOrProvinces on cci.AddressStateID equals sp1.ID into t15 from rt15 in t15.DefaultIfEmpty()
join sp2 in StateOrProvinces on cci.AddressProvinceID equals sp2.ID into t16 from rt16 in t16.DefaultIfEmpty()
join sp3 in StateOrProvinces on rt2.LegalAddressStateID equals sp3.ID into t17 from rt17 in t17.DefaultIfEmpty()
join sp4 in StateOrProvinces on rt2.LegalAddressProvinceID equals sp4.ID into t18 from rt18 in t18.DefaultIfEmpty()
select new {
cci.ID, cci.OwnerFirstName, cci.OwnerLastName, cci.CompanyName, cci.AddressLine1, cci.AddressLine2,
cci.AddressLine3, cci.AddressLine4, cci.AddressLine5, cci.AddressCity, StateAbbreviation = rt15.Abbreviation,
ProvinceAbbreviation = rt16.Abbreviation, cci.AddressPostalCode, CountryName = rt11.Name,
RegionName = rt12.Name, cci.AddressNote, cci.Phone1, cci.Phone2, cci.Phone3, cci.Phone4, cci.Phone5,
cci.Fax1, cci.Fax2, cci.Fax3, cci.Fax4, cci.Fax5, cci.Email1, cci.Email2, cci.Email3, cci.Email4,
cci.Email5, cci.CompanyWebSite, rt1.EIN, rt1.SSN, rt2.LegalName, rt2.LegalAddressLine1, rt2.LegalAddressLine2,
rt2.LegalAddressLine3, rt2.LegalAddressLine4, rt2.LegalAddressLine5, rt2.LegalAddressCity,
LegalAddressStateAbbreviation = rt17.Abbreviation, LegalAddressProvinceAbbreviation = rt18.Abbreviation,
rt2.LegalAddressPostalCode, LegalAddressCountryName = rt13.Name, LegalAddressRegionName = rt14.Name,
rt2.LegalAddressNote, rt3.FirstMonthFiscalYear, rt3.FirstMonthIncomeTaxYear,
TaxForm = rt6.TaxForm + " - (" + rt6.Description + ")",
rt4.CryptoPassPhrase, rt4.CryptoVector, rt4.CryptoMinSALTLen, rt4.CryptoMaxSALTLen, rt4.CryptoKeySize, rt4.CryptoHash,
rt4.CryptoSALT, rt4.CryptoIterations, rt5.AccountCode, rt5.UseAnalytics,
CreatedBy = rt9.LastName + ", " + rt9.FirstName + " " + rt9.MiddleName,
rt7.CreatedByID, rt7.CreatedDateTime,
ModifiedBy = rt10.LastName + ", " + rt10.FirstName + " " + rt10.MiddleName,
rt7.ModifiedByID, rt7.ModifiedDateTime, rt7.SiteDescription, rt8.SMTPServer, rt8.SMTPUserName,
rt8.SMTPPassword, rt8.SMTP_TO, rt8.SMTP_CC, rt8.SMTP_BCC, rt8.SMTPEncoding
}).ToList();
q.Dump();

Recreating this SQL to LINQ (C#, NET 4.5)

I have to query the database and to do so requires that I do quite a few inner joins and a couple of left outer joins. I've generated the SQL in a view but I am now having a bit of difficulty rewriting it to LINQ in my applications data layer.
FROM dbo.Organisation
INNER JOIN
dbo.EducationCourseVenue
INNER JOIN
dbo.EducationCourseVenueLocation ON dbo.EducationCourseVenue.Id = dbo.EducationCourseVenueLocation.EducationCourseVenueId ON
dbo.Organisation.GlobalEntityGUID = dbo.EducationCourseVenue.GlobalEntityGUID
INNER JOIN
dbo.CommunicationType
INNER JOIN
dbo.CommunicationTypeGlobalEntityMap ON dbo.CommunicationType.Id = dbo.CommunicationTypeGlobalEntityMap.CommunicationTypeId ON
dbo.EducationCourseVenue.GlobalEntityGUID = dbo.CommunicationTypeGlobalEntityMap.GlobalEntityGUID
INNER JOIN
dbo.Country
INNER JOIN
dbo.Address ON dbo.Country.Id = dbo.Address.CountryId
INNER JOIN
dbo.CountryRegion ON dbo.Country.RegionId = dbo.CountryRegion.Id ON
dbo.CommunicationTypeGlobalEntityMap.CommunicationTypeItemId = dbo.Address.Id
LEFT OUTER JOIN
dbo.AddressPostalDistrictMap
INNER JOIN
dbo.RegionItemDistrictMap ON dbo.AddressPostalDistrictMap.Id = dbo.RegionItemDistrictMap.Id
INNER JOIN
dbo.RegionTypeItem ON dbo.RegionItemDistrictMap.RegionTypeItemId = dbo.RegionTypeItem.Id ON
dbo.Address.Id = dbo.AddressPostalDistrictMap.AddressId
LEFT OUTER JOIN
dbo.RHSGarden
INNER JOIN
dbo.AddressGeographics ON dbo.RHSGarden.Id = dbo.AddressGeographics.NearestRHSGardenId ON dbo.Address.Id = dbo.AddressGeographics.AddressId
WHERE (dbo.CommunicationType.Code = 'AD')
This particular line of SQL is a problem for in LINQ
FROM dbo.Organisation
INNER JOIN
dbo.EducationCourseVenue
INNER JOIN
dbo.EducationCourseVenueLocation ON dbo.EducationCourseVenue.Id = dbo.EducationCourseVenueLocation.EducationCourseVenueId ON
dbo.Organisation.GlobalEntityGUID = dbo.EducationCourseVenue.GlobalEntityGUID
I don't know how to do a join in LINQ without specifying key joins and then doing another join below that.
Any ideas?

var q = from o in context.Organisation
join v in context.EducationCourseVenue on o.GlobalEntityGUID equals v.GlobalEntityGUID
join l in context.EducationCourseVenueLocation on v.Id equals l.EducationCouseVenueId
Is how i think of it, since your:
FROM dbo.Organisation
INNER JOIN
dbo.EducationCourseVenue
INNER JOIN
dbo.EducationCourseVenueLocation ON dbo.EducationCourseVenue.Id = dbo.EducationCourseVenueLocation.EducationCourseVenueId ON
dbo.Organisation.GlobalEntityGUID = dbo.EducationCourseVenue.GlobalEntityGUID
Corresponds to:
FROM dbo.Organisation as o
INNER JOIN dbo.EducationCourseVenue as v ON o.GlobalEntityGUID = v.GlobalEntityGUID
INNER JOIN dbo.EducationCourseVenueLocation as l ON v.Id = l.EducationCourseVenueId

LINQ: Inner join 2 table + outer join 1 table

I have 2 inner joins (3 tables) but I don't know and I find it hard to implement my research about outer join in LINQ. How do I change the last inner join to outer join, such that column will still join even if the column (Role) is null?
Here's an existing SQL version of this which I want to convert to LINQ:
SELECT dbo.EmployeeAccess.id, dbo.EmployeeAccess.EmpNo, dbo.EmployeeAccess.RoleID, dbo.EmployeeAccess.Active, dbo.EmployeeAccessLevel.Role,
dbo.View_HCM.LNameByFName
FROM dbo.EmployeeAccess LEFT OUTER JOIN
dbo.EmployeeAccessLevel ON dbo.EmployeeAccess.RoleID = dbo.EmployeeAccessLevel.id INNER JOIN
dbo.View_HCM ON dbo.EmployeeAccess.EmpNo = dbo.View_HCM.EmpNo
LINQ I now have with 2 inner joins:
(from ea in context.EmployeeAccesses
join vh in context.View_HCM on (Int16)ea.EmpNo equals vh.EmpNo
join rl in context.EmployeeAccessLevels on ea.RoleID equals rl.id
select new EmployeeWithEmail{
EmpNum = ea.EmpNo ?? 0,
EmailAddress = vh.EmailAddress,
LNameByFname = vh.LNameByFName,
Active2 = ea.Active ?? false
}).ToList();
}

Linq's outer join syntax uses 2 parts. First an into then DefaultIfEmpty
In your case, an outer join might look like this:
(from ea in context.EmployeeAccesses
join vh in context.View_HCM on (Int16)ea.EmpNo equals vh.EmpNo
join rl in context.EmployeeAccessLevels on ea.RoleID equals rl.id into outer_join
from subjoin in outer_join.DefaultIfEmpty()
select new EmployeeWithEmail{
EmpNum = ea.EmpNo ?? 0,
EmailAddress = vh.EmailAddress,
LNameByFname = vh.LNameByFName,
Active2 = ea.Active ?? false
}).ToList();
There are many tutorials on how to create the outer join in LINQ.

How to use AND operator in LINQ Join

I have following SQL Query
SELECT * FROM KDMS_dynamic vd
INNER JOIN KDMS_definition tblKDMS ON tblKDMS.SystemID=vd.SystemID
LEFT OUTER JOIN KDMS_typeid tblKDMSType ON tblKDMS.TypeId=tblKDMSType.TypeId
INNER JOIN KDMS_configuration tblKDMSConfig ON tblKDMS.SystemID=tblKDMSConfig.SystemID
AND tblKDMSConfig.ConfigurationDate = (SELECT MAX(ConfigurationDate)
FROM KDMS_configuration vc
WHERE vc.SystemID=tblKDMSConfig.SystemID)
AND vd.LastUpdated=(SELECT MAX(LastUpdated) FROM KDMS_dynamic vd
WHERE vd.SystemID=tblKDMS.SystemID)
WHERE
DeletionDate IS NULL
AND LongDescription IS NOT NULL
AND tblKDMS.TypeId <> 1
As I have try convert the same in to LINQ but I can not due to AND OPERATOR use in Inner Join.
I am not aware how to use And Operator in LINQ , JOIN
As folloing the linq code which i try.
IQueryable<getKDMS> query = (from VD in this._db.GetTable<KDMS_dynamic>()
join TblKDMS in this._db.GetTable<KDMS_definition>() on VD.SystemID equals TblKDMS.SystemID
join TblKDMSType in this._db.GetTable<KDMS_typeid>().DefaultIfEmpty() on TblKDMS.TypeID equals TblKDMSType.TypeID
join TblKDMSConfig in this._db.GetTable<KDMS_configuration>() on TblKDMS.SystemID equals TblKDMSConfig.SystemID
&& TblKDMSConfig.ConfigurationDate == (from TblKDMS_conf in this._db.GetTable<KDMS_configuration>()
where TblKDMS_conf.SystemID == TblKDMSConfig.SystemID
select TblKDMS_conf.ConfigurationDate).Max())
As i have try with && but it did not work....

it is done as on new{x.field1,x.field2} equals new{y.field1,y.field2}
var somedata = (from TblKDMS_conf in this._db.GetTable<KDMS_configuration>()
where TblKDMS_conf.SystemID == TblKDMSConfig.SystemID select TblKDMS_conf.ConfigurationDate).Max();
Queryable<getKDMS> query = (from VD in this._db.GetTable<KDMS_dynamic>()
join TblKDMS in this._db.GetTable<KDMS_definition>() on VD.SystemID equals TblKDMS.SystemID
join TblKDMSType in this._db.GetTable<KDMS_typeid>().DefaultIfEmpty() on TblKDMS.TypeID equals TblKDMSType.TypeID
join TblKDMSConfig in this._db.GetTable<KDMS_configuration>() on new {TblKDMS.SystemID,TblKDMSConfig.ConfigurationDate} equals new{TblKDMSConfig.SystemID,somedata}

Move the AND condition to your WHERE clause. Writing
SELECT * FROM Table1
INNER JOIN Table2 ON *first condition* AND *second condition*
WHERE *third condition*
is exactly the same as writing
SELECT * FROM Table1
INNER JOIN Table2 ON *first condition*
WHERE *second condition* AND *third condition*

I think you need to use the where operator in place of the &&.

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