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ASP.NET using Entity Framework display data to drop down list with distinct [closed]

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Please I need to implement distinct in a.CompanyName but it doesn't work. What do I need to do ?
try
{
var listCompany = company.CompanyList();
companyList1.DataSource = listCompany.Select(a => new { a.CompanyName, a.CompanyId }).Distinct();
companyList1.DataTextField = "CompanyName";
companyList1.DataValueField = "CompanyId";
companyList1.DataBind();
}
catch (Exception)
{
throw;
}

You can use with .GroupBy()
Groups the elements of a sequence.
companyList1.DataSource = listCompany
.GroupBy(x => x.CompanyName)
.Select(a => new
{ CompanyName = a.First().CompanyName, CompanyId = a.First().CompanyId });
Above query will group your result by company name and then will select CompanyName and CompanyId of first record
Try out online

Get NOT IN on a one to many relationship using LINQ [closed]

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I have a table LookUpRole as so
LookUpRoleId | RoleName
another table called UserAccounts as so
UserAccountId | FirstName | LastName
another table called UserRole as so
UserRoleId | LookUpRoleId | UserAccountId
This is what I have come up with:
using (var db = new AMSEntities())
{
var roleList = (from lur in db.LookUpRoles
join ur in db.UserRoles on lur.LookUpRoleId equals ur.LookupRoleId
join ua in db.UserAccounts on ur.UserId equals ua.UserAccountId
where ua.UserAccountId == accountId
select new UserRole()
{
LookupRoleId = lur.LookUpRoleId,
UserId = ua.UserAccountId
}).ToList();
var lackingRoles = db.UserRoles.Where(x => !roleList.Contains(x.LookupRoleId)).ToList();
}
A UserAccountId may have multiple LookUpRoleId. I just want to get the list of RoleName or LookUpRoleId that is not related to the UserAccountId yet. For example; UserAccountId of 1 has LookUpRoleId of 1 and 2. I need to get the RoleName of LookUpRoleId 3 and 4 using LINQ. Thank you.

Use a left join from the roles to the user-roles. Then query those that are null:
var result = from role in db.LookUpRoles
join ur in db.UserRole
on { role.LookUpRoleId, accountId } equals new {ur.LookUpRoleId, ur.UserAccountId } into j
from ur in j.DefaultIfEmpty()
where ur == null
select role.RoleName;
You can also do:
var result = from role in db.LookUpRoles
where !db.UserRole.Any(ur => ur.UserAccountId == accountId && ur.LookUpRoleId == role.LookUpRoleId)
select role.Name;

Query with case statement from SQL Server to Linq query c# [closed]

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I have the following query in sql server
select COUNT(mc_owner) as nbr ,
case mc_owner when 'Element1' then 'Element1' else 'others' end Owner
from [dbo].[full]
where (date_reception > '01-01-2015')
group by (CASE mc_owner WHEN 'Element1' THEN 'Element1' ELSE 'others' END)
order by nbr desc
I need to convert it to entityframework linq query

Try this,
var result = fulltableData.Where(x=>x.date_reception > '01-01-2015')
.GroupBy(x=> x.mc_owner.Equals("Element1")?"Element1":"others")
.Select(x=> new{ nbr = x.Count(), Owner = x.Key})
.OrderByDescending(x=>x.nbr);

I understand you want to select the number of occurrences of a certain mc_owner compared to all others. The following LINQ query should produce the same result:
full.Where(f => f.date_reception > new DateTime(2015, 1, 1))
.GroupBy(f => f.mc_owner == "Element1" ? f.mc_owner : "others")
.OrderByDescending(group => group.Count())
.Select(group => new { Owner = group.key, nbr = group.Count());

Linq to Sql Search through Tags [closed]

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Ok so I have these tables:
Video
Id
Title
VideoTag
Id
VideoId
TagId
Tag
Id
Name
I need a LINQ to SQL query to perform a search on the Videos, either by the title or by the tags.
For the moment all I have is this for searching by the title:
IQueryable<Video> videos =
from v in ctx.Videos
where v.Title.Contains(SearchString)
select
new Video
{
Id = v.Id,
Title = v.Title
};

Try this:
from v in ctx.Videos
join vt in ctx.VideoTags on v.Id equals vt.VideoId
join t in ctx.Tag on vt.TagId equals t.Id
where v.Title.Contains(SearchString) || t.Name.Contains(SearchString)
select
new Video
{
Id = v.Id,
Title = v.Title
};

How to re-write this linq from query syntax to method syntax? [closed]

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As in title, how to rewrite this linq query into method syntax?
(from row in recordsEpP
where (!string.IsNullOrEmpty(row.Column20)
&& !string.IsNullOrEmpty(row.Column14)
&& string.IsNullOrEmpty(row.Column8))
select new ReportDto{
Status = "P",
ContractNumber = row.ContractNumber,
Count = 1
}).ToList();

You could try something like this:
recordsEpP.Where(row=> !string.IsNullOrEmpty(row.Column20) &&
!string.IsNullOrEmpty(row.Column14) &&
string.IsNullOrEmpty(row.Column8)
).Select(row => new ReportDto{
Status = "P",
ContractNumber = row.ContractNumber,
Count = 1
}).ToList();