I have a sql statement as below, I want to translate it into Linq
select *
from
(
select Top 12 *
from DailyData
where ddaCode = '600000' and ddaDate < '2008/12/31'
order by ddaDate desc) as X
order by ddaDate
How can I do it? Thank you.
The From subquery becomes your first Linq query. Then this is queried in the second one.
var fromResults = DailyData.Where(x => x.ddaCode == "600000"
&& x.ddaDate < new DateTime(2008,12,31)
.OrderByDescending(x => x.ddaDate)
.Take(12);
var results = fromResults.OrderBy(x => x.ddaDate)
Related
I have this linq code that I need to translate into identical SQL so I can query the database directly... I get stuck when it gets complicated. Can anyone help?
Linq
_db.BatchPaymentSplits
.Where(bps => bps.YearSetupId == i.YearSetupId)
.Where(bps => bps.CustomerIdEntered != null)
.Where(bps => _db.BatchPayments
.Where(bp => _db.Batches.Where(b => b.BatchTypeId.Equals("T"))
.Select(b => b.BatchId)
.Contains(bp.BatchId)
)
.Select(bp => bp.BatchPaymentId).Contains(bps.BatchPaymentId)
)
SQL so far
SELECT * FROM BatchPaymentSplit
WHERE YearSetupId = 1
AND CustomerIdEntered IS NOT NULL
I can't say that I think the LINQ or the resulting SQL is the best way to express this query (should be using Join I think), but this is my literal translation:
SELECT *
FROM BatchPaymentSplits bps
WHERE bps.YearSetupId = i.YearSetupId AND
bps.CustomerIdEntered IS NOT NULL AND
EXISTS (SELECT * FROM BatchPayments bp
WHERE EXISTS (SELECT * FROM Batches b
WHERE b.BatchTypeId = 'T' AND
b.BatchId = bp.BatchId) AND
bp.BatchPaymentId = bps.BatchPaymentId)
You can translate Contains when applied to an IEnumerable/IQueryable as an EXISTS query with an = expression.
How to change the following SQL query to Linq query and how to convert results to a list of strings?
select Name
from Categories
where ID in (select CID from CategoryLink where VID = 57)
Please, provide some extra context. From the fist sight the code should be something like this:
List<string> names = db.Categories
.Where(c => db.CategoryLink.Any(cl=>cl.VID == 57 && CID == c.ID))
.ToList();
I have used too much time (days) on this and I really hope someone can help me out.
I found a good article on describing my problem in a generic way so let's stick to it.
I am trying to build this query but NHibernate fails to build the correct sql and returns a sql query exception.
Column vSagsAendring.Id is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. It could not execute the following query:
select
viewsagsae0_.Id as Id155_,
viewsagsae0_.SagId as SagId155_,
viewsagsae0_.JournalNr as JournalNr155_,
viewsagsae0_.LbfNr as LbfNr155_,
viewsagsae0_.OrgNr as OrgNr155_,
viewsagsae0_.OrgNavn as OrgNavn155_,
viewsagsae0_.AfdNavn as AfdNavn155_,
viewsagsae0_.SagsType as SagsType155_,
viewsagsae0_.Status as Status155_,
viewsagsae0_.SagsbehandlerInit as Sagsbeh10_155_,
viewsagsae0_.Dato as Dato155_,
viewsagsae0_.JournalAktionType as Journal12_155_,
viewsagsae0_.Beskrivelse as Beskriv13_155_,
viewsagsae0_.Ekstern as Ekstern155_
from vSagsAendring viewsagsae0_
group by viewsagsae0_.SagId
var query = from p in _session.Query<ViewSagsAendring>()
group p by p.SagId
into grp
select grp.OrderByDescending(g => g.Dato).First();
This is another version also took from the article:
var query = from p in _session.Query<ViewSagsAendring>()
group p by p.SagId
into grp
let maxDato = grp.Max(g => g.Dato)
from p in grp
where p.Dato == maxDato
select p;
It's have been a long journey, but now it's over. I hope that I can help someone else in the same situation by answering my own question.
var aendring = from sagsAendring in _session.Query<ViewSagsAendring>()
where sagsAendring.Dato ==
(
from innersagsAendring in _session.Query<ViewSagsAendring>()
where innersagsAendring.SagId == sagsAendring.SagId
select innersagsAendring.Dato
).Max()
select sagsAendring;
var result = aendring.ToList();
And because you can chain linq statements you can build a linq filter like this
if(Filters.VisInterneAendringer == false)
query = query.Where(x => x.Ekstern == true);
if (Filters.VisKunNyesteAendringer)
{
query = query.Where(sagsAendring => sagsAendring.Dato ==
(
from innerSagsAendring in Session.Query<ViewSagsAendring>() where innerSagsAendring.SagId == sagsAendring.SagId
select innerSagsAendring.Dato
).Max());
}
return query;
Your queries seem legit for LINQ in EntityFramework.
I'm not sure about hibernate, you might try to use QueryOver API instead of Query
http://nhibernate.info/blog/2009/12/17/queryover-in-nh-3-0.html
I am trying to work out how to covert the script below from SQL in to LINQ. Any help would be welcome.
SELECT *
FROM
[tableName]
WHERE
[MyDate] IN
(SELECT
MAX([MyDate])
FROM
[tableName]
GROUP BY
[MyID])
I can't find an equivalent for the "IN" clause section. There are existing questions on this forum but none that cover selecting a DateTime.
Thanks in advance.
You can use the ".Contains(..)" function:
e.g.
var itemQuery = from cartItems in db.SalesOrderDetails
where cartItems.SalesOrderID == 75144
select cartItems.ProductID;
var myProducts = from p in db.Products
where itemQuery.Contains(p.ProductID)
select p;
Although it looks like 2 round trips, as the LINQ only constructs the query when the IEnumerable is tripped, you should get reasonable performance.
I think Any() is what you are looking for:
var result = tableName.Where(x =>
(from t in tableName
group t by t.MyID into g
where g.Max(y => y.MyDate) == x.MyDate
select 1).Any())
Using SQL Server 2005 I've run a query like this
SELECT *
FROM mytable
WHERE (LEFT (title, 1) BETWEEN #PREFIXFROM AND #PREFIXTO)
I use this to do alphabet filtering, so for example
PREFIXFROM = a
PREFIXTO = c
and I get all the items in mytable between a and c (inclusive)
How do I do this in linq?
Selecting all the records fine.. but
1) how do I do the "LEFT" operation
and 2) How do I do a <= type operator with a non numeric field?
Any ideas appreciated!
Don't think of the SQL - think of what you're trying to achieve, and how you'd do it in .NET. So you're trying to get the first character, and work out whether it's between 'a' and 'c':
var query = from row in mytable
where row.title[0] >= 'a' && row.title[0] <= 'c'
select row;
or in dot notation:
var query = mytable.Where(row => row.title[0] >= 'a' && row.title[0] <= 'c');
Alternatively:
var query = mytable.Where(row => row.title.Substring(0, 1).CompareTo("a") >= 0 &&
row.title.Substring(0, 1).CompareTo("c") <= 0));