I try to join two collection into one. If my second is empty I just need a null value, here is my code (it's correct if com is not empty)
var tmp = List{ Elem {long UserID; string tmpContent} };
var com = List{ Comment{long UserID; string Content} } ;
var res = from t in tmp
group t by t.UserID into g
join c in com on g.Key equals c.UserID
select new AnswerSet(new List<Answer>(g), c.Content);
I would like to get AnswerSet(g, Content) ou AnswerSet(g, null) the problem, I guess, is with g.Key equals c.UserID when com is empty
Basically what you want is a left outer join. you can do that by using join into instead of just join.
var res = from t in tmp
group t by t.UserID into g
join c in com on g.Key equals c.UserID into j
from subc in j.DefaultIfEmpty()
select new AnswerSet(new List<Answer>(g), subc != null ?subc.Content : null);
Related
I'm trying to write a query that contains multiple left joins in linq in a c# .netcore 2.2 application. I've tried writing the query in linq but it is not properly retrieving all the rows. Query I'm trying to convert is as follows.
select ISNULL(b.Id, '00000000-0000-0000-0000-000000000000') as 'Bat Id', p.Id as 'ProductId', p.RP, u.UnitName as 'UnitName', ISNULL(b.QTY,0) as 'BusQty', p.[Name] as 'Product Name'
from Products p left join Bat b
ON p.Id = b.ProductId
left join Units u on p.UOId = u.Id;
linq I have so far
var allProducts = (from p in _db.Products
join s in _db.Bat on p.Id equals s.ProductId into ps
from s in ps.DefaultIfEmpty()
join u in _db.Units on p.UOId equals u.Id
select new
{
BatId = s.Id == null ? Guid.NewGuid() : s.Id,
RP = p.RP,
BusQty = s.QTY == null ? 0 : s.QTY,
ProductName = p.Name,
UnitName = u.UnitName,
ProductId = p.Id,
}).ToList();
You are missing DefaultIfEmpty() on Units, thereby turning it into an inner join
var allProducts = (
from p in _db.Products
join s in _db.Bat on p.Id equals s.ProductId into ps
from s in ps.DefaultIfEmpty()
join u in _db.Units on p.UOId equals u.Id into us
from u in us.DefaultIfEmpty()
select new
{
BatId = s.Id ?? Guid.NewGuid(),
RP = p.RP,
BusQty = s.QTY ?? 0,
ProductName = p.Name,
UnitName = u.UnitName,
ProductId = p.Id,
}).ToList();
I'm working with the following linq query:
var docList = from c in container.DocumentDeliveryPreferences
join o in container.Documents on c.DocumentId equals o.DocumentId
select new { o.Name, o.DocumentType, c.CustomerId };
How can I modify this to select only Documents where c.CustomerId equals X(some paramenter)?
You could try something the following:
var docList = from c in container.DocumentDeliveryPreferences
join o in container.Documents
on c.DocumentId equals o.DocumentId
where c.CustomerId == X
select new { o.Name, o.DocumentType, c.CustomerId };
where X is your parameter.
i have a query like this
WITH CTE_KELOMPOKINFORMASI (KelompokInformasi, XBRLItem_ItemId)
AS (
SELECT a.Id AS KelompokInformasi, c.XBRLItem_ItemId
FROM XBRLNamespaces a INNER JOIN XBRLHypercubes b
ON a.XBRLView_ViewId = b.XBRLView_ViewId
INNER JOIN XBRLHypercubeDimensionItems c
ON b.XBRLHypercubeId = c.XBRLHypercube_XBRLHypercubeId
WHERE a.Id like '%KBIK_AAKL%')
SELECT f.KelompokInformasi, e.Name AS DimensionName, c.Id AS Domain,
d.Text AS Description FROM [dbo].[XBRLDefinitionRoleDomainItems] a
INNER JOIN [dbo].[XBRLDefinitionRoleDimensionItems] b
ON a.XBRLDefinitionRole_DefinitionRoleId = b.XBRLDefinitionRole_DefinitionRoleId
INNER JOIN XBRLItems c ON a.XBRLItem_ItemId = c.ItemId
INNER JOIN XBRLLabels d
ON a.XBRLItem_ItemId = d.XBRLItem_ItemId
INNER JOIN XBRLItems e
ON b.XBRLItem_ItemId=e.ItemId
INNER JOIN CTE_KELOMPOKINFORMASI f
ON b.XBRLItem_ItemId=f.XBRLItem_ItemId
WHERE b.XBRLItem_ItemId=f.XBRLItem_ItemId
i want to move this sql query to linq, i realized that CTE is impossible in LINQ. So i divide into 2 parts. First i create a var like this:
var KelompokInformasi = from x in ent.XBRLNamespaces
join y in ent.XBRLHypercubes on x.XBRLView_ViewId equals y.XBRLView_ViewId
join z in ent.XBRLHypercubeDimensionItems on y.XBRLHypercubeId equals z.XBRLHypercube_XBRLHypercubeId
where x.Id.Contains("KBIK")
select new
{
x.Id,
y.XBRLItem_ItemId
};
and in second part i create:
_list = (from a in ent.XBRLDefinitionRoleDomainItems
join b in ent.XBRLDefinitionRoleDimensionItems on a.XBRLDefinitionRole_DefinitionRoleId equals b.XBRLDefinitionRole_DefinitionRoleId
join c in ent.XBRLItems on a.XBRLItem_ItemId equals c.ItemId
join d in ent.XBRLLabels on a.XBRLItem_ItemId equals d.XBRLItem_ItemId
join e in ent.XBRLItems on b.XBRLItem_ItemId equals e.ItemId
join f in KelompokInformasi on b.XBRLItem_ItemId equals (int)f.XBRLItem_ItemId
where (b.XBRLItem_ItemId == (int)f.XBRLItem_ItemId)
select new MappingDomainRepository
{
KI = f.Id,
Dimension = e.Name,
Domain = c.Id,
Description = d.Text
}).ToList();
Where _list is from List<MappingDomainRepository> _list = new List<MappingDomainRepository>();
in my code above, i want to join my _list to var KelompokInformasi. In var kelompokInformasi I've got 47 rows but in _list I've got 0 data return.
What's wrong in my code? is it possible to join my _list to var kelompokInformasi?
You need to change the second part to:
var other = (from a in ent.XBRLDefinitionRoleDomainItems
join b in ent.XBRLDefinitionRoleDimensionItems on a.XBRLDefinitionRole_DefinitionRoleId equals b.XBRLDefinitionRole_DefinitionRoleId
join c in ent.XBRLItems on a.XBRLItem_ItemId equals c.ItemId
join d in ent.XBRLLabels on a.XBRLItem_ItemId equals d.XBRLItem_ItemId
join e in ent.XBRLItems on b.XBRLItem_ItemId equals e.ItemId
join f in KelompokInformasi on b.XBRLItem_ItemId equals (int)f.XBRLItem_ItemId
where (b.XBRLItem_ItemId == (int)f.XBRLItem_ItemId)
select new MappingDomainRepository
{
KI = f.Id,
Dimension = e.Name,
Domain = c.Id,
Description = d.Text,
XBRLItem_ItemId = a.XBRLItem_ItemId
};
...which adds in the XBRLItem_ItemId which use to join to the CTE.
Then join the two together. We have other (above) and KelompokInformasi from the CTE:
var result = from x in KelompokInformasi
join o in other on x.XBRLItem_ItemId equals o.XBRLItem_ItemId
select new {KelompokInformasi = o.KelompokInformasi,
DimensionName = o.Name,
Domain = o.Id,
Description = o.Text
};
..which appears to be the columns you exentually select.
I'm trying to join two tables and to display the Join result into GridView in WinForms, but something is going wrong...
it's not giving me Error message or something, Please help!!
my code :
var temp = teacherCmbBx.SelectedItem.ToString();
var temp2 = (from c in context.Teachers
where temp == c.FirstName
select c).ToList();
long num = temp2[0].ID;
var teacherGroup = (from t in context.Teachers
join g in context.Groups on t.ID equals g.TeacherID
where num == t.ID
select t);
teachergrpGridView.DataSource = teacherGroup;
string temp3 = (string)teachergrpGridView.Rows[rowNum].Cells[0].Value;
You are almost there. You are just missing .ToList()
var teacherGroup = (from t in context.Teachers
join g in context.Groups on t.ID equals g.TeacherID
where num == t.ID
select t).ToList();
teachergrpGridView.DataSource = teacherGroup;
var teacherGroup = from t in context.Teachers
join g in context.Groups on t.ID equals g.TeacherID
where num == t.ID
select new {
t.Id ,
g.Name,
t.xxxx
};
do you know how write this SQL Query to linq ?
SELECT *
FROM
a
INNER JOIN b
ON a.FkSubmissionId = b.Id
RIGHT JOIN c
ON a.FkItemId = c.Id
WHERE
(b.FkUserId = '...' OR b.FkUserId is null)
and
(c.FkTenderId = 2)
I use Linquer and the best I have from the tool is that :
Linq :
from
items in _context.Items
from
si in _context.si
join s in _context.s
on new { fki = si.fki } equals new { fki = s.Id }
into
submissions_join
from
s in submissions_join.DefaultIfEmpty()
...
Result in SQL :
SELECT *
FROM
[Items] AS [t0]
CROSS JOIN [SubmissionsItems] AS [t1]
LEFT OUTER JOIN [Submissions] AS [t2]
ON [t1].[FkSubmissionId] = [t2].[Id]
WHERE
(([t2].[FkUserId] = #p0) OR (([t2].[FkUserId]) IS NULL))
AND
([t0].[FkTenderId] = #p1)
So the final result it not what I get from the query I need...
Thank you for your help !!!
Try this:
var part1 =
from x in a
join y in b on x.FkSubmissionId equals y.Id
where b.FkUserId = "..."
select new {x, y};
var part2 =
from c in z
where c.FkTenderId == 2
join xy in part1
on z.Id equals xy.x.FkItemId
into xys
from xy in xys.DefaultIfEmpty()
select new {xy.x, xy.y, z};
I would reorder your query so you can use a left join instead of a right join
var query = from c in context.C
from a in context.A.Where(x => c.Id == x.FkItemId)
.DefaultIfEmpty()
join b in context.B on a.FkSubmissionId equals b.id
where b.FkUserId == '...' || b.FkUserId == null
where c.FkTenderId == 2
select new {
a,
b,
c
};