Linq select in query in c# - linq

I have two lists containing data.
List<changeLogUsers> users;
UserID
List<changeLogQualifications> userQualifications;
UserID
QualificationID
I want to select only those userQualifications for which UserID is available in users list.
Can anyone help?


var result = userQualifications.Where(u => users.Any(x => x.UserID == u.UserID));


Try this
List<changeLogQualifications> userQualifications.Select(p=>p.UserID!=null);


Or alternatively:
var results = from uq in userQualifications
join u in users on uq.UserID equals u.UserID
select uq;

Related

LINQ Query To Return Duplicates Exclusively

I'm working on this LINQ query. I'd like the resulting list return a list of records that contain duplicates exclusively, based on the EMailAddress1 field and grouped by the EMailAddress1 field.
For instance:
emailaddress1#gmail.com
emailaddress1#gmail.com
emailaddress2#gmail.com
emailaddress2#gmail.com
emailaddress2#gmail.com
emailaddress3#gmail.com
emailaddress3#gmail.com
etc.
Any advice on this? Thanks.
var contacts = (from c in xrm.ContactSet
where c.StateCode != 1
orderby c.EMailAddress1, c.CreatedOn
descending select new {
c.FirstName,
c.LastName,
c.EMailAddress1,
c.ContactId,
c.CreatedOn }).ToList();

Based on your previous query:
var duplicatedEmails = (from c in contacts
group c by c.EMailAddress1 into g
where g.Count() > 1
select g.Key).ToList();
var duplicatedContacts = contacts.Where(c => duplicatedEmails.Contains(c.EMailAddress1));

Dynamic select in query with linq

I see Dynamic linq in below link:
ScottGu
I want to use this method to select a dynamic query like this:
I have a complex select and this way not solve my problem,
this is my select:
Select sUserName,sname, sFamily,sMobail,sid,sNumberSt,sActive,sPic,sDate from Student where {0} order by sid desc";
which {0} is a complex Condition:
sname like %somthing% and susername=N'something' and sid in (select sidfk from tablex where userteacher=N'name1')
and this condition is passed to method.
I must say that:
I don's know my condition,my condition specified with user search params.this condition that I say,Is only one example of what I want to do.
How can I do this?

Only way that solve my problem:
I send tow parameters instead of one,one for student and one for tablex:
var az = db.tablex.Where(p => p.userteacher== name1)
.Select(p => p.sidfk).ToList();
var query = db.Students.Where(textSearch).Where(s=>az.Contains(s.sid)).OrderByDescending(s => s.sid)
.Select(s => new
{
s.sUserName,
s.sname,
s.sFamily,
s.sMobail,
s.sid,
s.sNumberSt,
s.sActive,
s.sPic,
s.sDate,
});
wiche textSearch is :
sname like %somthing% and susername=N'something'
with dynamic linq
any better way is exist?

You don't need to use dynamic linq for this situation.
string paramA = "", paramB = "";
var query = from x in context.table1
where x.name == paramA
where context.table2.Where(y => y.field1 == paramB).Any(y => y.id == x.id)
select x;

Dynamic Linq usually use if in query you don't know what field will be use, so in your sample you use only params for conditions with field, so you don't ned dynamic linq
you can little optimize you query like this
var query = from student in db.Students
join teacher in db.tablex on student.sid equals teacher.sidfk
where student.sname.Contains('somthing') &&
susername=='something' &&
teacher.userteacher=='name1'
orderby s.sid descending
select new
{
s.sUserName,
s.sname,
s.sFamily,
s.sMobail,
s.sid,
s.sNumberSt,
s.sActive,
s.sPic,
s.sDate,
};

LINQ - using a query expression to calculate data time difference

I use EntityFramework 4, LINQ, and C#.
I need display data in a GridView from a query expression using Linq; I need project as anonymous type a value calculate on fly DateTime.UtcNow - cl.DateLocked Note: cl.DateLocked is of type DateTime and I need to know how many days of difference between this two dates.
With this query I receive an error:
DbArithmeticExpression arguments must have a numeric common type.
Any idea how to do it in Linq? If Linq does not allow it how to do it in a different way?
Thanks for your time
var queryContentsLocked = from cl in context.CmsContentsLockedBies
join cnt in context.CmsContents
on cl.ContentId equals cnt.ContentId
join u in context.aspnet_Users
on cl.UserId equals u.UserId
select new
{
cl.DateLocked,
cnt.ContentId,
cnt.Title,
u.UserName,
u.UserId,
TimePan = DateTime.UtcNow - cl.DateLocked // Problem here!!!
};

var queryContentsLocked = from cl in context.CmsContentsLockedBies
join cnt in context.CmsContents
on cl.ContentId equals cnt.ContentId
join u in context.aspnet_Users
on cl.UserId equals u.UserId
select new
{
cl.DateLocked,
cnt.ContentId,
cnt.Title,
u.UserName,
u.UserId,
Days = SqlFunctions.DateDiff("day", cl.DateLocked, DateTime.UtcNow)
};

Without using any SqlFunction
var grandTotalWork = (from t in db.AssignmentHandymandetails
join ad in db.AssignmentDetails on t.assignment_detail_id equals ad.assignment_detail_id
where ad.assignment_id == Convert.ToInt32(Label_assignmentId.Text)
select new { startTime = t.started_time.Value.TimeOfDay, endTime = t.end_time.Value.TimeOfDay, TotalWorkTime = (t.started_time.Value.TimeOfDay.Duration() - t.end_time.Value.TimeOfDay.Duration()).Duration()});
then you can bind the result in GridView you wish

Try this:
DateTime.UtcNow.Subtract(cl.DateLocked).TotalDays

LINQ Query Similar to SQL WHERE x IN

I have a need to create a LINQ query that returns results based on a subquery. Not quite sure I'm wording that properly but the best way I know to ask is to show an example. How can I turn the following TSQL query into a LINQ query (tables are same name as objects):
SELECT CuisineId, Name
FROM Cuisine
WHERE CuisineId NOT IN (SELECT CuisineId
FROM RestaurantCuisine
WHERE RestaurantId = #id)
As you can guess, I'm trying to get a list of "available" cuisines to be listed for a user to add to a list of cuisines that a restaurant offers. The LINQ I have thus far returns ALL cuisines and doesn't take in account of the existing CuisineId's that have already been added to the other table:
I've looked all over for an example but not quite sure how to describe exactly what I need. I looked at the MSDN reference for LINQ queries but couldn't find anything like what I need:
MSDN LINQ Sample Queries
Anyone able to give me an example?

In C#:
var query =
from c in db.Cuisine
where !(from rc in db.RestaurantCuisine
where rc.RestaurantId == id
select rc.CuisineId)
.Contains(c.CuisineId)
select new {
c.CuisineId,
c.Name
};
In VB.NET:
Dim availableCuisines = _
From c In db.Cuisines _
Where Not (From rc In db.RestaurantCuisines _
Where rc.RestaurantId = id _
Select rc.CuisineId) _
.Contains(c.CuisineId) _
Select c

var cuisines = db.Cuisine.Where(c => !RestaurantCuisine.Any(
rc => rc.RestaurantId == c.Id && rc.CuisineId == c.CuisineId);

Try:
Cuisine.Where(c => !RestaurantCuisine.Select(rc => rc.CuisineID).Contains(c.CuisineID)).Select(c => c);

var query = (from c in Cuisine
where !(from rest in RestaurantCuisine
where (rest.RestaurantID == id)).Contains(c.CuisineId)
select new
{
CuisineID = c.CuisineID,
Name = c.Name
});

Random linq result

I have this LINQ query:
var agnts = (from a in db.agents select new { a.UserId, a.name }).Take(10);
How can I get randomly get 10 records from my agents table?
I have tried:
agnts = agnts.OrderBy(n => Guid.NewGuid());
but this doesn't seem to do anything.
I would appreciate anybody's help on this.
Thanks,
Louis

Then you do
agnts = agnts.OrderBy(n => Guid.NewGuid());
after
var agnts = (from a in db.agents select new { a.UserId, a.name }).Take(10);
agents are already taken. You need to specify OrderBy() before Take()

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