I'm using LINQ to join 2 datatables:
var JoinResult = (from p in WZdt.AsEnumerable()
join t in WZIdt.AsEnumerable()
on p.Field<string>("ID") equals t.Field<string>("ID")
select new
{
p,
t
}).ToList();
WZdt and WZIdt are DataTables. Normally, when wanted to specify columns I would write something like this:
var JoinResult = (from p in WZdt.AsEnumerable()
join t in WZIdt.AsEnumerable()
on p.Field<string>("ID") equals t.Field<string>("ID")
select new
{
FileNo = p.Field<string>("FileNo"),
Title = p.Field<string>("Title"),
M1 = t.Field<int?>("M1"),
RecCount = t.Field<int?>("RecCount")
}).ToList();
But those source datatables are created dynamically based on some logic, so they can differ when it comes to Columns they have. I would like to apply similiar logic to the select part of LINQ, but I don't know how. Can I construct array of columns somehow, like [p.FileNo, p.Title, t.M1, t.RecCount] ?
Or any other way?
Related
I have two related tables. Then I use LINQ to query Data.
this is my code
var items = await (from a in queryable
join b in _context.TUserGrant on a.UserNo equals b.UserNo
join c in _context.TProviderInfo on a.ProviderNo equals c.ProviderNo
orderby a.BillNo
select new
{
a.BillNo,
a.NotificeBillNo,
makeName = b.UserName,
a.MakeDate,
a.ProviderNo,
c.ProviderName,
a.CheckTime,
a.CheckAddress,
a.CheckName,
a.StatusTitle,
}).ToListAsync();
My problem is that I need all the columns of the first table, which is all the values of A.
I also need some columns from table B.
I wonder if there is an easy way to get these columns.
Instead of setting them one by one in the SELECT method.
You can try this
var items = await (from a in queryable
join b in _context.TUserGrant on a.UserNo equals b.UserNo
join c in _context.TProviderInfo on a.ProviderNo equals c.ProviderNo
orderby a.BillNo
select new
{
tabA = a,
makeName = b.UserName
}).ToListAsync();
I wrote query in Linq to SQL. I need to put left join between db.secs and db.subs i.e. with db.subs being left table and the db.secs being right.
I wrote this but cannot figure out how to do that?
var qry = (from sr in db.secs
join s in db.subs
on sr.Id equals s.secId
join ss in db.subsSt
on s.Id equals ss.subId
join u in db.usersNew
on s.uid equals u.Id
where ss.isNew
group s by new { s.uid, u.UName, sr.Id, sr.Name } into totalGrp
select new
{
CreatorName = totalGrp.Key.UName,
SecName = totalGrp.Key.Name,
TotalRecs = totalGrp.Count()
}).OrderBy(o => o.CreatorName)
.ToList();
How do I make it re-arrange like first table?
In angular and HTML I am looping through collection and presenting in table.
You have to use DefaultIfEmpty() on the second table to generate the outer join or use navigation properties on the store. Something along the lines of
var query = from sr in db.secs
join s in db.subs into secSubs
from srs in secSubs.DefaultIfEmpty()
// rest of the query follows
Alternatively with navigation properties you might be able to do something like
var query = from sr in db.secs
from s in sr.Subs
select new {sr, s}
A third option is to possibly use a quasi ANSI-82 syntax rather than ANSI-92 join syntax and make the first item above more pallatable:
var query = from sr in db.secs
from s in db.Subs.Where(s1 => s1.subId == sr.Id).DefaultIfEmpty()
select new {sr, s}
I wrote up a more detailed post on this a while back at https://www.thinqlinq.com/Post.aspx/Title/Left-Outer-Joins-in-LINQ-with-Entity-Framework.
I need to join the two tables of a DataGrid, but I only want the values with the same id (idviagem is pk in table idviagem and is fk in table idpassageiro)
I don't know how to do the query, in that moment I only take the table tbpassageiro on the grid, and I want to join them on DataGrid when the keys are equals
using (checkinEntities1 db = new checkinEntities1())
{
var qcheckin = (from c in db.tbpassageiro
join g in db.tbviagem on c.idviagem equals g.idviagem
where c.idviagem == g.idviagem
select c).ToList();
gridpass.ItemsSource = qcheckin;
}
The binding I know 100% is correct (some values from table passageiro and the other Biding values from table tbviagem)
This what I want to do:
If you want columns from both tables, then you have to create a view model for the columns which you want from both tables.
using (checkinEntities1 db = new checkinEntities1())
{
var qcheckin = (from c in db.tbpassageiro
join g in db.tbviagem on c.idviagem equals g.idviagem
where c.idviagem == g.idviagem
select new viewModelName()
{
//get the column values here like
Hora = c.Hora,
Partida = g.Partida
}).ToList();
gridpass.ItemsSource = qcheckin;
}
Hope this will give you the answer you are looking for.
When I need to join some tables using linq, and when those tables consist of a lot of fields, it takes a lot of work to get all the data that I need. For instance:
var result = from i in Person
join y in Works
on i.PID euqals y.PID
join z in Groups
on y.GID on z.GID
select new {Name = i.Name, Work = y.work, WG = z.GroupName};
How can make the query return all the tables ?
I guess what you need is simply this :
var Query = from x in Table_1
join y in Table_2
on x.id equals y.id
where x.Country.Equals("X Country")
select new {x,y};
So I have two DataTables that have the same schema, but different data. I want to join the two tables together where two fields, id3 and print and the same. How would I write this in LINQ?
Right now, this works and gives no compiler errors:
var singOneJoin =
from prod in singOneProd.Table.AsEnumerable()
join agg in singOneAgg.Table.AsEnumerable()
on prod.Field<string>("print") equals agg.Field<string>("print")
select new
{
print = prod.Field<string>("print")
};
But what I really want is this:
var singOneJoin =
from prod in singOneProd.Table.AsEnumerable()
join agg in singOneAgg.Table.AsEnumerable()
on (prod.Field<string>("print") equals agg.Field<string>("print") &&
prod.Field<Int32>("id3") equals agg.Field<Int32><("id3"))
select new
{
print = prod.Field<string>("print")
};
But this gives me compiler errors.
How do I join these two tables together on both the print and the id3 columns?
Regards,
Kyle
Use anonymous objects to join on multiple fields:
var singOneJoin =
from prod in singOneProd.Table.AsEnumerable()
join agg in singOneAgg.Table.AsEnumerable()
on new {
Print = prod.Field<string>("print"),
Id3 = prod.Field<Int32>("id3")
} equals new {
Print = agg.Field<string>("print"),
Id3 = agg.Field<Int32>("id3")
}
select new {
print = prod.Field<string>("print")
};
Keep in mind that anonymous object property names should match.