我想使用linq-to-sql查询，它将使用内部联接和左外部联接（使用.DefaultIfEmpty（）），但查询不起作用。这是我在T-SQL中的一个简单任务。 这是我的疑问：
var results = from cy in _dc.Companies
join cyv in _dc.CompanyVersions
on cy.CompanyId equals cyv.CompanyId
join cyd in _dc.CompanyDetails
on cyv.CompanyVersionId equals cyd.Id
join cd in _dc.CustomerDetails
on cy.CompanyId equals cd.CompanyId
join d in _dc.Documents
on cd.CustomerId equals d.CustomerId
join di in _dc.DocumentItems
on d.DocumentId equals di.DocumentId
join dd in _dc.DocumentDetails
on di.DocDetailsId equals dd.DocumentDetailsId
join dt in _dc.DetailTypes
on dd.detailTypeId equals dt.detailTypeId
join vt in _dc.Vats
on dt.VATCode equals vt.VATCode
join v in _dc.Vouchers.DefaultIfEmpty()
on dd.DocumentDetailsId equals v.DocDetailID
join cc in _dc.CreditCards.DefaultIfEmpty()
on v.CCType equals cc.CCType
where
(d.DocTypeId == 1 || d.DocTypeId == 2) && (d.DocDate >= date)
&&
(d.DocDate < date.AddDays(1)) &&
(d.CompanyVersionId == cyv.CompanyVersionId)
&& (d.isDeleted == false || d.isDeleted == null)
orderby d.DocNumber ascending
select new
{
d.DocumentId,
d.DocNumber,
d.AutUser,
d.GrossAmount,
d.DocTypeId,
cyd.Name,
cyd.AddressLine1,
cyd.AddressLine2,
cyd.TelephoneLine,
cyd.FaxLine,
v.FromVoucNbr,
d.DocDate,
cd.CustomerName,
cd.StreetAddress,
cd.City,
cd.Country,
dt.DetDescr,
cc.CCType,
dd.FreeDescr,
dd.NetAmount,
dd.VATAmount,
vt.VATDescr,
cc.Description,
vt.VATRate
};
任何人都可以建议我如何在此查询的最后2个表中使用左外连接？
答案 0 :(得分：1)
您错误地放置了.DefaultIfEmpty。
我认为它是这样的（虽然我不确定where子句..）。
var results =
from cy in _dc.Companies
join cyv in _dc.CompanyVersions on cy.CompanyId equals cyv.CompanyId
join cyd in _dc.CompanyDetails on cyv.CompanyVersionId equals cyd.Id
join cd in _dc.CustomerDetails on cy.CompanyId equals cd.CompanyId
join d in _dc.Documents on cd.CustomerId equals d.CustomerId
join di in _dc.DocumentItems on d.DocumentId equals di.DocumentId
join dd in _dc.DocumentDetails on di.DocDetailsId equals dd.DocumentDetailsId
join dt in _dc.DetailTypes on dd.detailTypeId equals dt.detailTypeId
join vt in _dc.Vats on dt.VATCode equals vt.VATCode
join v in _dc.Vouchers on dd.DocumentDetailsId equals v.DocDetailID into other1
from o1 in other1.DefaultIfEmpty()
join cc in _dc.CreditCards on v.CCType equals cc.CCType into other2
from o2 in other2.DefautlIfEmtpy()
where (d.DocTypeId == 1 || d.DocTypeId == 2)
&& (d.DocDate >= date)
&& (d.DocDate < date.AddDays(1))
&& (d.CompanyVersionId == cyv.CompanyVersionId)
&& (d.isDeleted == false || d.isDeleted == null)
orderby d.DocNumber ascending
select new
{
d.DocumentId,
d.DocNumber,
d.AutUser,
d.GrossAmount,
d.DocTypeId,
cyd.Name,
cyd.AddressLine1,
cyd.AddressLine2,
cyd.TelephoneLine,
cyd.FaxLine,
o1.FromVoucNbr,
d.DocDate,
cd.CustomerName,
cd.StreetAddress,
cd.City,
cd.Country,
dt.DetDescr,
o2.CCType,
dd.FreeDescr,
dd.NetAmount,
dd.VATAmount,
vt.VATDescr,
o2.Description,
vt.VATRate
};
答案 1 :(得分：0)
是的，连接的顺序是不正确的，我现在修复它，这是工作和编译的查询：
P.S。谢谢大家的帮助！
var results =
from cy in _dc.Companies
join cyv in _dc.CompanyVersions on cy.CompanyId equals cyv.CompanyId
join cyd in _dc.CompanyDetails on cyv.CompanyVersionId equals cyd.Id
join cd in _dc.CustomerDetails on cy.CompanyId equals cd.CompanyId
join d in _dc.Documents on cd.CustomerId equals d.CustomerId
join di in _dc.DocumentItems on d.DocumentId equals di.DocumentId
join dd in _dc.DocumentDetails on di.DocDetailsId equals
dd.DocumentDetailsId
join dt in _dc.DetailTypes on dd.detailTypeId equals dt.detailTypeId
join vt in _dc.Vats on dt.VATCode equals vt.VATCode
join v in _dc.Vouchers on dd.DocumentDetailsId equals v.DocDetailID into
other1
from o1 in other1.DefaultIfEmpty()
join cc in _dc.CreditCards on o1.CCType equals cc.CCType into other2
from o2 in other2.DefaultIfEmpty()
where (d.DocTypeId == 1 || d.DocTypeId == 2)
&& (d.DocDate >= date)
&& (d.DocDate < date.AddDays(1))
&& (d.CompanyVersionId == cyv.CompanyVersionId)
&& (d.isDeleted == false || d.isDeleted == null)
orderby d.DocNumber ascending
select new
{
d.DocumentId,
d.DocNumber,
d.AutUser,
d.GrossAmount,
d.DocTypeId,
cyd.Name,
cyd.AddressLine1,
cyd.AddressLine2,
cyd.TelephoneLine,
cyd.FaxLine,
o1.FromVoucNbr,
d.DocDate,
cd.CustomerName,
cd.StreetAddress,
cd.City,
cd.Country,
dt.DetDescr,
o2.CCType,
dd.FreeDescr,
dd.NetAmount,
dd.VATAmount,
vt.VATDescr,
o2.Description,
vt.VATRate
};