I'm trying to convert my SQL statement to a Linq statement and I'm not sure how to add the second COUNT to it. This is my SQL statement
SELECT l.Campus_Name, Labs = COUNT(*), LabsWithSubnets = COUNT(s.Lab_Space_Id)
FROM vw_Lab_Space l
LEFT JOIN vw_Subnet s on l.Lab_Space_Id = s.Lab_Space_Id
GROUP BY l.Campus_Name
ORDER BY 1
and this is my LINQ statement so far:
from l in Vw_Lab_Space
from s in Vw_Subnet
.Where(s => s.Lab_Space_Id == l.Lab_Space_Id)
.DefaultIfEmpty() // <=- triggers the LEFT JOIN
group l by new { l.Campus_Name } into g
orderby g.Key.Campus_Name
select new {
Campus_Name = g.Key.Campus_Name,
Labs = g.Count()
}
So I have everything but the LabsWithSubnets part in there. I'm just not sure how to add that in as I can't just do an s.Lab_Space_id.Count() in the select statement.
If you need table structure and sample data please see Need help creating an OUTER JOIN to count spaces.
Using your query as a basis, you need the groups to include s so you can count when non-null (I also removed the unnecessary anonymous object around the grouping key):
from l in Vw_Lab_Space
from s in Vw_Subnet
.Where(s => s.Lab_Space_Id == l.Lab_Space_Id)
.DefaultIfEmpty() // <=- triggers the LEFT JOIN
group new { l, s } by l.Campus_Name into g
orderby g.Key
select new {
Campus_Name = g.Key,
Labs = g.Count(),
LabsWithSubnets = g.Count(ls => ls.s != null)
}
However, rather than translate the SQL, I would probably take advantage of LINQ's group join to handle the query slightly differently:
var ans = from l in Vw_Lab_Space
join s in Vw_Subnet on l.Lab_Space_Id equals s.Lab_Space_Id into sj
group new { l, sj } by ls.Campus_Name into lsjg
select new {
Campus_Name = lsjg.Key,
NumLabs = lsjg.Count(),
LabsWithSubnets = lsjg.Sum(lsj => lsj.sj.Count())
};
PS Even in your query, I would use join...from...DefaultIfEmpty rather than from...from...where but depending on your database engine, may not matter.
Related
I'm having trouble getting my Linq statemnt to work when doing an outer join and a group by. Here's a SQL version of what I'm trying to accomplish:
select p.PRIMARY_KEY, min(p.EFFECTIVE_DATE), sum(IsNull(c.PAID_INDEMNITY, 0))
from PRMPOLCY p
left outer join CLMMAST c on p.PRIMARY_KEY = c.POLICY_NO
where p.UNDERWRITER_UID = 93
GROUP BY p.PRIMARY_KEY
Here's what I have in Linq (which doesn't work):
var result = from p in context.PRMPOLCies
join c in context.CLMMASTs on p.PRIMARY_KEY equals c.POLICY_NO into polClm
where (p.UNDERWRITER_UID == underwriter)
from grp in polClm.DefaultIfEmpty()
group grp by p.PRIMARY_KEY into g
select new PolicySummation()
{
PolicyNo = g.Key,
Incurred = g.Sum(grp => grp.PAID_INDEMNITY ),
EffDate = g.Min(grp => grp.PRMPOLCY.EFFECTIVE_DATE
};
Beating my head against the wall trying to figurwe this out!
Assuming you have a navigation property set up between PRMPOLCY and CLMMAST, you shouldn't need to specify the join explicitly. It's much easier to express most queries in linq without explicit joins, but rather treating your structures as a hierarchy. I don't know the specifics of your model property names, but I'd take a guess that something like this would work.
var result =
from p in context.PRMPOLCies
where (p.UNDERWRITER_UID == underwriter)
select new PolicySummation {
PolicyNo = p.PRIMARY_KEY,
Incurred = p.CLMASTs.Select(c => c.PAID_INDEMNITY).DefaultIfEmpty().Sum(),
EffDate = p.EFFECTIVE_DATE,
};
You need to include both your tables in the group clause like this:
group new { p, grp } by p.PRIMARY_KEY into g
Then in your Sum / Min
g.Sum(grp => grp.grp == null ? 0 : grp.grp.PAID_INDEMNITY )
g.Min(grp => grp.p.PRMPOLCY.EFFECTIVE_DATE)
var abc1 = from dlist in db.DebtorTransactions.ToList()
join war in db.Warranties on dlist.ProductID equals war.Id
join ag in db.Agents on war.fldAgentID equals ag.pkfAgentID
join sr in db.SalesReps on war.fldSrId equals sr.pkfSrID
where dlist.TransTypeID == 1
select new
{
dlist.Amount,
dlist.TransTypeID,
name = ag.Name,
ag.pkfAgentID,
sr.pkfSrID,
salesnam = sr.Name
} into objabc
group objabc by new
{
objabc.TransTypeID,
objabc.name,
objabc.salesnam,
objabc.Amount
};
var amt1 = abc1.Sum(x => x.Key.Amount);
var abc2 = from dlist in db.DebtorTransactions.ToList()
join cjt in db.CarJackaTrackas on dlist.ProductID equals cjt.pkfCjtID
join ag in db.Agents on cjt.AgentID equals ag.pkfAgentID
join sr in db.SalesReps on cjt.SalesRepId equals sr.pkfSrID
where dlist.TransTypeID == 0
select new
{
dlist.Amount,
dlist.TransTypeID,
name = ag.Name,
ag.pkfAgentID,
sr.pkfSrID,
enter code here` salesnam = sr.Name
} into objabc
group objabc by new
{
objabc.TransTypeID,
objabc.name,
objabc.salesnam,
objabc.Amount
};
var amt2 = abc1.Sum(x => x.Key.Amount);
//var result1=
return View();
i am new to linq, this query is working but i need to get the sum of Amount where dlist.TransTypeID == 0 and where dlist.TransTypeID == 1 by just single query. may anybody help me? thanks in advance
Here's a trimmed down example of how you can do it. You can add the joins if they are necessary, but I'm not clear on why you need some of the extra join values.
var transTypeAmountSums = (from dlist in db.DebtorTransactions
group dlist by dlist.TransTypeId into g
where g.Key == 0 || g.Key == 1
select new
{
TransTypeId = g.Key,
AmountSum = g.Sum(d => d.Amount)
}).ToDictionary(k => k.TransTypeId, v => v.AmountSum);
int transTypeZeroSum = transTypeAmountSums[0];
int transTypeOneSum = transTypeAmountSums[1];
A couple of things to note:
I removed ToList(). Unless you want to bring ALL DebtorTransactions into memory then run a Linq operation on those results, you'll want to leave that out and let SQL take care of the aggregation (it's much better at it than C#).
I grouped by dlist.TransTypeId only. You can still group by more fields if you need that, but it was unclear in the example why they were needed so I just made a simplified example.
Work on DF 4 vs 2010.Face problem on join on SalSalesOrderDetail with SalSalesOrderFinancial table.
In SalSalesOrderFinancial one record have SalesOrderDetailID=null. Want to get those records whose SalesOrderDetailID is not present in SalSalesOrderFinancial.
To get desired out put write bellow linq syntax,it’s working .Looking for better join syntax .Is there any way to get desired in one join.
var tempBDwithSODetail = (from p in this.Context.SalSalesOrderFinancials
where p.SalesOrderDetailID != null
select p.SalesOrderDetailID).AsEnumerable();
var tempBDwithOutSODetail = (from p in this.Context.SalSalesOrderFinancials where p.SalesOrderDetailID == null select p).AsEnumerable();
var querySOD = (this.Context.SalSalesOrderDetails.Where(item => !tempBDwithSODetail.Contains(item.SalesOrderDetailID))).AsEnumerable();
var tempBDetail = (from p in querySOD
join q in tempBDwithOutSODetail on p.SalesOrderID equals q.SalesOrderID
where q.SalesOrderDetailID == null
select new
{
q.SalesOrderID,
p.SalesOrderDetailID,
q.CurrencyID,
q.BillingPolicyID,
q.BillTypeID,
q.BillingTypeID
}).AsEnumerable();
If have any query please ask.Thanks in advanced.
if i got you, you just need to simple left join between SalSalesOrderDetail and SalSalesOrderFinancial...
var query = (from u in this.Context.SalSalesOrderDetail
join t in this.Context.SalSalesOrderFinancials
on u.SalesOrderDetailID equals t.SalesOrderDetailID into JoinedList
from t in JoinedList.DefaultIfEmpty()
select new
{
SalSalesOrderDetail = t,
SalSalesOrderFinancials = u
})
.Where(u => u.SalSalesOrderFinancials == null)
.ToList();
I am trying to get from 3 related tables by using LINQ. But when I use 2 joins, the result takes only elements getting from 2nd join. Here is my code:
var myAssList = mldb.Assigns
.Join(mldb.Lists,
a => a.list_id,
l => l.id,
(a, l) => new {
Assign = a,
List = l
})
.Where(a => a.Assign.assigned_to == "myname")
.Join(mldb.Elements,
li => li.List.id,
e => e.parent_server_id,
(li, e) => new {
Element = e
});
var jsonSerialiser = new JavaScriptSerializer();
var listListJson = jsonSerialiser.Serialize(myAssList);
this Json return only attributes from Element(e) and List(li). But I want to get also the attributes from Assign(a).
The SQL query I am trying to realize in LINQ is that:
select * from Assigns
inner join Lists
on Assigns.server_list_id=Lists.id
inner join Elements
on Lists.id=Elements.parent_id
where Assigns.assigned_to='myname'
So, how can I get the attributes from the first join also (from "a", "l" and "e")?
You can access Assign entity from outer sequence li variable:
.Join(mldb.Elements,
li => li.List.id,
e => e.parent_server_id,
(li, e) => new {
Element = e,
Assign = li.Assign // here
});
from a in mldb.Assigns
join l in mldb.Lists on a.list_id equals l.id
join e in mldb.Elements on l.id equals e.parent_server_id
where a => a.Assign.assigned_to == "myname"
select new { Assign = a, Element = e }
This is so called "query syntax". It makes LINQ expressions looks like SQL queries.
In the end they are translated to IEnumerable extension methods. If you want
to join multiple tables then query syntax is more readable. Another useful feature
of query syntax is let clause. With the aid of it, you can declare additional variables
inside your queries.
I want to know how to make Linq expression that has the same effect as these SQL query
SELECT item.*, priceforitem.*
FROM
item
LEFT JOIN priceforitem
ON priceforitem.ItemID = item.ItemID
AND priceforitem.PriceID = ?PriceID
I already make it using the Method query but I don't know if it will produce the same result
db.Items
.GroupJoin(
db.PriceForItems.Where(pi => pi.PriceID == id),
i => i.ItemID,
pi => pi.ItemID,
(i, pi) => new { Item = b, Prices = pi })
.SelectMany(
a => a.Prices.DefaultIfEmpty(),
(i, pi) => new
{
ItemID = i.Item.ItemID,
Code = i.Item.Code,
Name = i.Item.Name,
PriceForItemID = pi.PriceForItemID,
Price = pi.Price
})
and then after thinking for awhile i shorten it like this
db.Items
.SelectMany(
i => db.PriceForItems.Where(
pi => pi.PriceID == id
&& pi.ItemID = i.ItemID).DefaultIfEmpty(),
(i, pi) => new
{
ItemID = i.Item.ItemID,
Code = i.Item.Code,
Name = i.Item.Name,
PriceForItemID = pi.PriceForItemID,
Price = pi.Price
})
I am new to Linq, and I don't know which is better and how to convert it to Linq query statement.
First of all your sql query. It is effectively and inner join because the where condition will filter out all rows where data from priceforitem is null. If you do want to convert same query to linq you can do it like
from i in db.Items
join p in db.PriceforItems on
i.ItemId equals p.ItemId into tempvals
from t in tempvals.DefaultIfEmpty()
where t.PriceId == id
select new{i.ItemId, ..., t.PriceId, t...., t....}
I mostly write linq queries instead of expressions where they are more readable to me. If you still want to get an expression, you can write a valid linq query and paste it into Linqpad and it will give the result as well as lambda expression of your query.