在LINQ中可以按多个组进行分组吗?
例如,我有这个查询(显然是不完整的)
from lxr in LOCATION_XREFs
join l in LOCATIONs on lxr.LOCATION_SKEY equals l.LOCATION_SKEY
join c in COMPANies on l.COMPANY_SKEY equals c.COMPANY_SKEY
join prlx in PeopleRoleLocationXrefs on lxr.LOCATION_XREF_SKEY equals prlx.LOCATION_XREF_SKEY
join p in PEOPLEs on prlx.PEOPLE_SKEY equals p.PEOPLE_SKEY
join pr in PeopleRoles on prlx.PeopleRoleKey equals pr.PeopleRoleKey..。我想回到一些公司,这些公司有一大堆地点,而这些公司又有一大群人。
发布于 2009-06-03 03:23:03
如果您希望按多个参数分组,这是可能的:
from lxr in LOCATION_XREFs
join l in LOCATIONs on lxr.LOCATION_SKEY equals l.LOCATION_SKEY
join c in COMPANies on l.COMPANY_SKEY equals c.COMPANY_SKEY
join prlx in PeopleRoleLocationXrefs on lxr.LOCATION_XREF_SKEY equals prlx.LOCATION_XREF_SKEY
join p in PEOPLEs on prlx.PEOPLE_SKEY equals p.PEOPLE_SKEY
join pr in PeopleRoles on prlx.PeopleRoleKey equals pr.PeopleRoleKey
group c by new { c.COMPANY_SKEY, l.LOCATION_SKEY} into myGroup
select new
{
myGroup.Key.COMPANY_SKEY,
myGroup.Key.LOCATION_SKEY,
myGroup.Count()
}发布于 2009-06-04 14:14:19
我最终使用了以下代码来实现我想要的功能。有趣的注意:注意,我想将角色展平并用逗号连接,所以我使用了一个使用聚合操作符的包装器访问器来实现这一点。显然,在LINQ查询中不支持聚合运算符,因为您得到的是"the query operator "Aggregate" is not supported",否则我就会像下面的Roles = new List<string>(g.Select(u => u.pr.RoleName)).Aggregate((a, b) => a + ", " + b)一样在这里内联地执行它
public class DAOPerson
{
public string Name { get; set; }
public int PeopleSkey { get; set; }
public List<string> RolesCollection { get; set; }
public string Roles
{
get { return RolesCollection.Aggregate((a, b) => a + ", " + b); }
}
}
IQueryable<DAOLocation> gridData;
gridData = (from lxr in db.LOCATION_XREFs
join l in db.LOCATIONs on lxr.LOCATION_SKEY equals l.LOCATION_SKEY
join c in db.COMPANies on l.COMPANY_SKEY equals c.COMPANY_SKEY
where lxr.DEPARTMENT_NUMBER == Department.BINDING_AUTHORITY_KEY
&& lxr.BRANCH_NUMBER == Branch.ATLANTAKEY
orderby c.NAME, l.INTERNAL_NAME ascending
select new DAOLocation
{
CompanyName = c.NAME,
CompanySkey = c.COMPANY_SKEY,
LocationName = l.INTERNAL_NAME,
LocationSkey = l.LOCATION_SKEY,
Persons = (from prlx in db.PeopleRoleLocationXrefs
join lxr2 in db.LOCATION_XREFs on prlx.LOCATION_XREF_SKEY equals lxr.LOCATION_XREF_SKEY
join p in db.PEOPLEs on prlx.PEOPLE_SKEY equals p.PEOPLE_SKEY
join pr in db.PeopleRoles on prlx.PeopleRoleKey equals pr.PeopleRoleKey
where lxr2.LOCATION_SKEY == l.LOCATION_SKEY
group new { p, pr } by p.PEOPLE_SKEY into g
select new DAOPerson
{
Name = g.First().p.LAST_NAME,
PeopleSkey = g.First().p.PEOPLE_SKEY,
RolesCollection = new List<string>(g.Select(u => u.pr.RoleName))
}).ToList()
});https://stackoverflow.com/questions/942894
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