I have a query which I ran successfully in SQL Server Management Studio, which returns the table values shown in the screenshot
The query I used is:
SELECT tcoid, COUNT(*) ownleasetank
FROM TankProfile
WHERE ownleasetank = 3
GROUP BY tcoid
Now I'm using Entity Framework to make things easier in my sample project.
I used this method to return the table values as array object:
public async Task<Object> GetLeaseInformationPrincipal()
{
ISOTMSEntities context = new ISOTMSEntities();
var testleaseinfo = from d in context.TankProfiles
join f in context.TankOperators
on d.tcoid equals f.tcoId
where (d.ownleasetank == 3)
select new { f.tcoName, d.ownleasetank } into x
group x by new { x.tcoName } into g
select new
{
tconame = g.Key.tcoName,
ownleasetank = g.Select(x => x.ownleasetank).Count()
};
return testleaseinfo.ToList();
}
but it is not working properly. I also tried other ways, when I use where and groupby method in Entity Framework it doesn't working properly for me.
Does anybody know the solution for this?
It's very simple with LINQ methods:
context.TankProfiles
.Where(t => t.ownleasetank = 3)
.GroupBy(t => t.tcoid)
.Select(g => new {g.Key, g.Count()})
.ToArray();
I have no idea why in your C# version of the query you have such opeartions such join, while your SQL query is very simple. You have to rethink that :)
var c = from t in context.TankProfile
where t.ownleasetank == 3
group t by t.tcoid into g
select new { tcoid=g.Key, ownleasetank=g.Select(x => x.ownleasetank).Count() };
return c.ToList();
Related
How do I get randomly similar data
me tried to merge different ones in the first stage but Different function does not work,
var turler= (from x in db.bird_table_ad
join e in db.kus_resim on x.tr_x equals e.kus_tur
where x.aile == item
select new GozlemTurleri
{
id = x.id,
kod = x.kod,
tr_x = x.tr_x,
en_x = x.en_x,
lt_x = x.lt_x,
turfotourl="image_resize.phpad="+e.altDIR+"/"+e.resim+"&yon="+(e.galeri=="fg"?"2":"HD2"),
aile = x.aile,
gfoto = x.gfoto
}).Distinct().ToList();
If you try to get distinct record with regarding to tr_x from database then you can use GroupBy in entity framework.
So your code will be.
.GroupBy(x => x.tr_x).Select(x => x.First()).ToList();
Instead of
.Distinct().ToList();
I had a look at Entity Framework, get object by ID.
I can't get that to work.
I specifically want the
WHERE [Extent1].[CatId] = 1
as I don't want to return everything that filter it as in
using (ApplicationContext db = new ApplicationContext())
{
IQueryable<Project> projects = db.Projects; // Get all
var p = (from i in db.Projects where i.Id == ProjectID select i);
Console.WriteLine("Project # {0} added and Named:{1} ", ProjectID, p.First().Name);
Assert.IsNotNull(projects.First().Name);
}
So what I am looking for in SQL terms is
SELECT *
FROM Projects
WHERE id = 1
Hope that makes sense.
You should be able to use LINQ fluent syntax:
var project = db.Projects.SingleOrDefault(i => i.Id == ProjectId);
Great LINQ reference and examples
Basically I'm trying to do this in LINQ to SQL;
SELECT DISTINCT a,b,c FROM table WHERE z=35
I have tried this, (c# code)
(from record in db.table
select new table {
a = record.a,
b = record.b,
c = record.c
}).Where(record => record.z.Equals(35)).Distinct();
But when I remove column z from the table object in that fashion I get the following exception;
Binding error: Member 'table.z' not found in projection.
I can't return field z because it will render my distinct useless. Any help is appreciated, thanks.
Edit:
This is a more comprehensive example that includes the use of PredicateBuilder,
var clause = PredicateBuilder.False<User>();
clause = clause.Or(user => user.z.Equals(35));
foreach (int i in IntegerList) {
int tmp = i;
clause = clause.Or(user => user.a.Equals(tmp));
}
var results = (from u in db.Users
select new User {
a = user.a,
b = user.b,
c = user.c
}).Where(clause).Distinct();
Edit2:
Many thanks to everyone for the comments and answers, this is the solution I ended up with,
var clause = PredicateBuilder.False<User>();
clause = clause.Or(user => user.z.Equals(35));
foreach (int i in IntegerList) {
int tmp = i;
clause = clause.Or(user => user.a.Equals(tmp));
}
var results = (from u in db.Users
select u)
.Where(clause)
.Select(u => new User {
a = user.a,
b = user.b,
c = user.c
}).Distinct();
The ordering of the Where followed by the Select is vital.
problem is there because you where clause is outside linq query and you are applying the where clause on the new anonymous datatype thats y it causing error
Suggest you to change you query like
(from record in db.table
where record.z == 35
select new table {
a = record.a,
b = record.b,
c = record.c
}).Distinct();
Can't you just put the WHERE clause in the LINQ?
(from record in db.table
where record.z == 35
select new table {
a = record.a,
b = record.b,
c = record.c
}).Distinct();
Alternatively, if you absolutely had to have it the way you wrote it, use .Select
.Select(r => new { a = r.a, b=r.b, c=r.c }).Distinct();
As shown here LINQ Select Distinct with Anonymous Types, this method will work since it compares all public properties of anonymous types.
Hopefully this helps, unfortunately I have not much experience with LINQ so my answer is limited in expertise.
I get the following error when trying to join an array to the Linq-to-EF query
An error occurred while executing the command definition. See the inner exception for details. Some part of your SQL statement is nested too deeply. Rewrite the query or break it up into smaller queries.
The code is as follows:
var vids = new List<string>();
using (var ctx = new MyDbContext())
{
var qry = ctx.Pickups.Where(p => p.UserName == User.Identity.Name);
if (someBoolean)
{
var v = GetVids(); // get the list of Ids from a web service
vids.AddRange(v);
}
if (vids.Count() > 0)
{
qry = qry.Join(vids, p => p.VId, v => v, (v, p) => p);
}
var data = qry
.Select(p => new
{
// etc.
});
}
The problem is that the web service is not associated with the DB I'm using EF with, otherwise, I'd just do the join against the tables in the DB. The number of Id's I get back from the web service could be upwards of a hundred or so (usually 5-10). If I comment out the Join, the code works fine, so I know the error is in the Join. With just a few (up to about 30) ids in vids, the join works perfectly.
What do you recommend to remedy this problem? The only thing I could think of was to insert the list of IDs into the DB and do the join that way. That doesn't seem too appealing to me.
Try to replace if (vids.Count() > 0) with:
if (vids.Count > 0)
{
qry = qry.Where(arg => vids.Contains(arg.VId));
}
This will work only if vids is less then 2100 elements, as this will be translated to IN (x, y, .., n) condition.
If you use entity framework 3.5, then Contains will not work. You can find possible solution here: 'Contains()' workaround using Linq to Entities?
How can I do this SQL query with Entity Framework?
SELECT DISTINCT NAME FROM TestAddresses
Using lambda expression..
var result = EFContext.TestAddresses.Select(m => m.Name).Distinct();
Another variation using where,
var result = EFContext.TestAddresses
.Where(a => a.age > 10)//if you have any condition
.Select(m => m.name).Distinct();
Another variation using sql like syntax
var result = (from recordset
in EFContext.TestAddresses
.where(a => a.city = 'NY')//if you have any condition
.select new
{
recordset.name
}).Distinct();
Try this:
var results = (from ta in context.TestAddresses
select ta.Name).Distinct();
This will give you an IEnumerable<string> - you can call .ToList() on it to get a List<string>.
The way that #alliswell showed is completely valid, and there's another way! :)
var result = EFContext.TestAddresses
.GroupBy(ta => ta.Name)
.Select(ta => ta.Key);
I hope it'll be useful to someone.
DBContext.TestAddresses.Select(m => m.NAME).Distinct();
if you have multiple column do like this:
DBContext.TestAddresses.Select(m => new {m.NAME, m.ID}).Distinct();
In this example no duplicate CategoryId and no CategoryName i hope this will help you
Entity-Framework Select Distinct Name:
Suppose if you are using Views in which you are using multiple tables and you want to apply distinct in that case first you have to store value in variable & then you can apply Distinct on that variable like this one....
public List<Item_Img_Sal_VIEW> GetItemDescription(int ItemNo)
{
var Result= db.Item_Img_Sal_VIEW.Where(p => p.ItemID == ItemNo).ToList();
return Result.Distinct().ToList();
}
Or you can try this Simple Example
Public Function GetUniqueLocation() As List(Of Integer)
Return db.LoginUsers.Select(Function(p) p.LocID).Distinct().ToList()
End Function
use Select().Distinct()
for example
DBContext db = new DBContext();
var data= db.User_Food_UserIntakeFood .Select( ).Distinct();
In order to avoid ORDER BY items must appear in the select list if SELECT DISTINCT error, the best should be
var results = (
from ta in DBContext.TestAddresses
select ta.Name
)
.Distinct()
.OrderBy( x => 1);
Entity-Framework Select Distinct Name:
Suppose if you are want every first data of particular column of each group ;
var data = objDb.TableName.GroupBy(dt => dt.ColumnName).Select(dt => new { dt.Key }).ToList();
foreach (var item in data)
{
var data2= objDb.TableName.Where(dt=>dt.ColumnName==item.Key).Select(dt=>new {dt.SelectYourColumn}).Distinct().FirstOrDefault();
//Eg.
{
ListBox1.Items.Add(data2.ColumnName);
}
}