I plan on using this in a subquery but can't figure out the correct syntax to translate the following query into LINQ:
select ChapterID, min(MeetingDate)
from ChapterMeeting
group by ChapterID
var query = myDataContext.ChapterMeeting
.GroupBy(cm => cm.ChapterID)
.Select(g => new {
g.Key,
MinMeetingDate = g.Min(cm => cm.MeetingDate)
});
Well, Amy beat me to it, but in case you wanted to see it with the "comprehension" syntax:
var q = (
from cm in context.ChapterMeeting
group cm by cm.ChapterID into cmg
select new {
ChapterID = cmg.Key,
FirstMeetingDate = cmg.Min(cm => cm.MeetingDate)});
Related
I have a SQL query which I want to convert to Linq.
This is my SQL query:
SELECT
Calisanlar.CalisanId,
CovidYakalanmaTarih,
CovidBitisTarih
FROM
Calisanlar
INNER JOIN
Covids ON Calisanlar.CalisanId = Covids.CalisanId
WHERE
Calisanlar.CalisanId IN (SELECT TOP 10 CalisanId
FROM Hastaliklar
GROUP BY CalisanId
ORDER BY COUNT(*) DESC)
AND DATEDIFF(DAY, CovidYakalanmaTarih, GETDATE()) BETWEEN 0 AND 30
I wrote this C# code, but it doesn't work as expected because i didn't write "DATEDIFF(DAY, CovidYakalanmaTarih, GETDATE()) BETWEEN 0 AND 30" linq version:
var query = context.Hastaliklar
.GroupBy(x => x.CalisanId)
.OrderByDescending(grp => grp.Count())
.Select(grp => grp.Key)
.Take(10)
.ToList();
var result = from hastalik in context.Hastaliklar
join covid in context.Covids
on hastalik.CalisanId equals covid.CalisanId
where query.Contains(hastalik.CalisanId)
&& EF.Functions.DateDiffDay(covid.CovidYakalanmaTarih, covid.CovidBitisTarih)
select new SonBirAyCovidDto
{
CalisanId = covid.CalisanId,
CovidYakalanmaTarih = covid.CovidYakalanmaTarih,
CovidBitisTarih = covid.CovidBitisTarih
};
There is not direct translation to BETWEEN in EF Core, but you can make other condition. Also it is better to remove ToList() from first query, in this case you will have only one roundtrip to database.
var query = context.Hastaliklar
.GroupBy(x => x.CalisanId)
.OrderByDescending(grp => grp.Count())
.Select(grp => grp.Key)
.Take(10);
var result =
from hastalik in context.Hastaliklar
join covid in context.Covids
on hastalik.CalisanId equals covid.CalisanId
where query.Contains(hastalik.CalisanId)
&& covid.CovidYakalanmaTarih <= covid.CovidBitisTarih
&& EF.Functions.DateDiffDay(covid.CovidYakalanmaTarih, covid.CovidBitisTarih) <= 30
select new SonBirAyCovidDto
{
CalisanId = covid.CalisanId,
CovidYakalanmaTarih = covid.CovidYakalanmaTarih,
CovidBitisTarih = covid.CovidBitisTarih
};
Can anybody please help with this SQL query to transform it to EF Linq Expression?
select MI.Id, B.Count, B.Cost, Name, Price, Unity, I.Count, I.Cost, BOL.Date, BOL.type, BOL.Number
from Balance B inner join MaterialsInfo MI on Mi.Id = B.MaterialsId
inner join Income I on MI.Id = I.MaterialsId
inner join BillOfLading BOL on I.BillOfLadingId = BOL.Id
where B.Id in (select Id from (select max(Date), Id from Balance group by Balance.MaterialsId))
and I.Id in (select Id from(select max(Date), Income.Id as Id from Income inner join BillOfLading BOL on Income.BillOfLadingId = BOL.Id group by Income.MaterialsId))
I've been trying to do this for days, so I could really use some help.
Do you need extra info?
Thank you in advance.
Edit
Here is a little part of the diagram, maybe it helps
It seems the subqueries in both of your conditions in where clause is incorrect. Because your
group by column is missing in the select statement
And it is very unclear what you trying to achieve from the subqueries.
Without a clear understanding of your subqueries, all I can prepare for you is this.
var result = await (from balance in yourDBContect.Balances
join material in yourDBContect.MaterialsInfos on balance.MaterialsId equals material.Id
join income in yourDBContect.Incomes on material.Id equals income.MaterialsId
join bill in yourDBContect.BillOfLadings on income.BillOfLadingId equals bill.Id
where Balances.GroupBy(g => g.MaterialsId)
.Select(s => new
{
MaterialsId = s.Key,
MaxDate = s.Max(x => x.Date)
}).ToList().Contains(new { balance.MaterialsId, MaxDate = balance.Date })
&& Incomes.Join(BillOfLadings,
p => p.BillOfLadingId,
e => e.Id,
(p, e) => new { p, e })
.GroupBy(g => g.p.MaterialsId)
.Select(s => new
{
MaterialsId = s.Key,
MaxDate = s.Max(s => s.e.Date)
}).ToList().Contains(new { income.MaterialsId, MaxDate = balance.Date })
select new
{
material.Id,
balance.Count,
balance.Cost,
balance.Name,
balance.Price,
balance.Unity,
ICount = income.Count,
ICost = income.Cost,
bill.Date,
bill.Type,
bill.Number
});
Notes:
Alias for Income.Count and Income.Cost are changed because an object cannot contain exactly same nenter code hereamed property.
Linq for a proper subquery will replace new List<int>().
I'm stumped trying to convert the following sql to linq:
SELECT t.* FROM(SELECT mwfieldid,MAX([TimeStamp]) AS MaxValue, BatchDocumentID
FROM mw_BatchField
GROUP BY mwfieldid,BatchDocumentID) x
JOIN mw_BatchField t ON x.mwfieldid = t.mwfieldid
AND x.MaxValue = t.TimeStamp
and x.BatchDocumentID = t.BatchDocumentID
So far I had to convert it to a stored proc to get it to work. I'd rather know how to write this correctly in linq. I tried using a sql to linq converter (http://www.sqltolinq.com/) which produced this code that had errors in it: (Are these converters any good? It didn't seem to produce anything useful with a few tries.)
From x In (
(From mw_BatchFields In db.mw_BatchFields
Group mw_BatchFields By
mw_BatchFields.MWFieldID,
mw_BatchFields.BatchDocumentID
Into g = Group
Select
MWFieldID,
MaxValue = CType(g.Max(Function(p) p.TimeStamp),DateTime?),
BatchDocumentID)
)
Join t In db.mw_BatchFields
On New With { .MWFieldID = CInt(x.MWFieldID), .MaxValue = CDate(x.MaxValue), .BatchDocumentID = CInt(x.BatchDocumentID) }
Equals New With { .MWFieldID = t.MWFieldID, .MaxValue = t.TimeStamp, .BatchDocumentID = t.BatchDocumentID }
Select
BatchFieldID = t.BatchFieldID,
BatchDocumentID = t.BatchDocumentID,
MWFieldID = t.MWFieldID,
TimeStamp = t.TimeStamp,
value = t.value,
DictionaryValue = t.DictionaryValue,
AutoFilled = t.AutoFilled,
employeeID = t.employeeID
Seems like a lot of code for such a simple query, and it doesn't compile.
So for every combination of mwfieldid and BatchDocumentID you want all columns of the row with the highest TimeStamp? This is something which is much easier to express in LINQ than SQL so I'm not surprised that an automated converter is making a meal of it.
You should be able to do:
Mw_BatchFields.GroupBy(x => new { x.Mwfieldid, x.BatchDocumentId })
.SelectMany(x => x.Where(y => y.TimeStamp == x.Max(z => z.TimeStamp)))
This (like your SQL) will return multiple rows per grouping key if there is more than one row in the group that shares the same maximum TimeStamp. If you only want row per key, you could use:
Mw_BatchFields.GroupBy(x => new { x.Mwfieldid, x.BatchDocumentId })
.Select(x => x.OrderByDescending(y => y.TimeStamp).First())
Edit:
Sorry, just twigged that you're working in VB, not C#, so not quite what you were looking for, but if you can live with the lambda syntax style, I think the above can be translated as:
Mw_BatchFields.GroupBy(Function(x) New With {x.Mwfieldid, x.BatchDocumentId}).Select(Function(x) x.OrderByDescending(Function(y) y.TimeStamp).First())
and:
Mw_BatchFields.GroupBy(Function(x) New With {x.Mwfieldid, x.BatchDocumentId}).SelectMany(Function(x) x.Where(Function(y) y.TimeStamp = x.Max(Function(z) z.TimeStamp)))
I'm not good with LINQ yet and could use some help with the syntax.
Thanks!
The below query needs to be written in LINQ for C#.
SELECT Galleries.GalleryTitle, Media.*
FROM Galleries
INNER JOIN Media ON Galleries.GalleryID = Media.GalleryID
WHERE (Galleries.GalleryID = 150)
ORDER BY MediaDate DESC, MediaID DESC
Or with query syntax:
var query = from g in db.Galleries
join m in db.Media on g.GalleryID equals m.GalleryID
where g.GalleryID == 150
orderby m.MediaDate descending, m.MediaID descending
select new { g.GalleryTitle, Media = m };
Something like this:
var query = db.Galleries
.Join(db.Media, g => g.GalleryID, m => m.GalleryID, (g, m) => new {g, m})
.Where(r.g.GalleryID == 150)
.Select(res => new {res.g.GalleryTitle, Media = res.m}
.OrderByDescending(o => o.Media.MediaDate)
.ThenByDescending(o => o.Media.MediaID);
select colId,
colTaskType,
MaxID
from tblTaskType
join (
select tblCheckList.colTaskTypeID,
max(colItemNumber) MaxID
from tblCheckList
group by colTaskTypeID
) x on coltaskTypeID = tblTaskType.colID
Assuming you are using linq-to-sql and have the two tables in a datacontext.
The more or less exact translation would be:
var maxChecks = from checks in DataContext.tblChecklist
group checks by checks.colTaskTypeID into g
select new { colTaskTypeID, max = g.Group.Max(x => x.colItemNumber) };
var result = from t in DataContext.tblTaskType
join c in maxChecks on t.colTaskTypeID equals c.colTaskTypeID
select new { t.colId, t.colTaskTypeID, c.max };
But you could try:
var result = from t in DataContext.tblTaskType
select new {
t.colId,
t.colTaskTypeID,
Max = (from c in DataContext.tblChecklist
where c.colTaskTypeID == t.colTaskTypeID
select c.colItemNumber).Max() };