What’s the opposite of . equals in C#?

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I’m doing a left Join where I want to pick up just what’s on the left table and there’s no right one.

I’m using LINQ and Entityframework. I made a code that takes the similarities, follows below:

var mQuery = from pessoa in clientes
                         from prod in produtos
                         on pessoa.grupo equals prod.grupo
                         Select New { pessoa.nome, prod.descricao }

Like I said, I’m training LINQ and Entity. I wanted a method that would necessarily do the opposite of equals. Note: the operator != did not work

Vlww

database .net entity-framework entity-framework-6 orm

  • o Linq no em left Join direto, é preciso usar alguns recursos, como agrupar e colocar nulo onde não encontrar, here is an example that can help you: https://docs.microsoft.com/en-us/dotnet/csharp/linq/perform-left-outer-joins

  • The model I picked up is from this link. My problem is not with left Join, which by the way, worked. But with the method of comparing objects

2 answers

2

You can use the except

Except is the LINQ extension method that subtracts elements from a collection. For example, this will remove elements of the first entities (List1) that are elements in the second entities (List2) and that will be returned as a third entity (List3).

var Lista3 = Lista1.Except(Lista2);

Another more complete example:

int[] Lista1 = { 5, 3, 9, 7, 5, 9, 3, 7 };  
int[] Lista2 = { 8, 3, 6, 4, 4, 9, 1, 0 }; 

int[] Lista3 = Lista1.Except(Lista2).ToArray(); 

Console.WriteLine("Resultado:");  
foreach (int num in Lista3){  
  Console.WriteLine("{0} ", num);  
}

Upshot: 7 and 5.

List1: Full select result.

List2: Select with data that should not appear.

Lista3: Result of the method except, bringing only different data from List2.

Note: That operator is like a not in.

  • I would have to throw Tabela1 and table2 dice on a list?

  • You would need to throw the dice into a array.

  • But then I stop using LINQ and use a common list structure, right?

  • You can continue using LINQ to carry out your select to bring data to List1 and List2.

  • 1

    if you have to load a large select and a large select, it will have a considerable impact on performance...

  • 2

    Agree @Cypherpotato, it would not be very performatic.

  • 1

    @Cypherpotato, I agree. But the challenge here was necessarily to use LINQ. I’m training different ways to do it. So another way of execution, in this case, is not very interesting to me.

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I found the answer I was looking for. There is no method that is opposite to .Equal. The name of what I was looking for was Outer Left Join. The challenge was that I wanted to use only the LINQ structure.

Goes below:

var permissoesCliente = from permi in context.tabelaPermissoes
                    join aces in context.tabelaAcessos
                    on permi.CodigoPermissao equals 
                    aces.CodigoPermissao into tt
                    from tabelaTemp in pp.DefaultIfEmpty()
                    where tabelaTemp == null
                    select new { permi.CodigoPermissao };

ref: https://forums.asp.net/t/1896048.aspx

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