How Would You Do a "Not In" Query with Linq

How would you do a not in query with LINQ?

I don't know if this will help you but..

NorthwindDataContext dc = new NorthwindDataContext();    
dc.Log = Console.Out;

var query =    
    from c in dc.Customers    
    where !(from o in dc.Orders    
            select o.CustomerID)    
           .Contains(c.CustomerID)    
    select c;

foreach (var c in query) Console.WriteLine( c );

from The NOT IN clause in LINQ to SQL by Marco Russo

NOT IN clause in LINQ to Entities

If you are using an in-memory collection as your filter, it's probably best to use the negation of Contains(). Note that this can fail if the list is too long, in which case you will need to choose another strategy (see below for using a strategy for a fully DB-oriented query).

   var exceptionList = new List<string> { "exception1", "exception2" };

   var query = myEntities.MyEntity
                         .Select(e => e.Name)
                         .Where(e => !exceptionList.Contains(e.Name));

If you're excluding based on another database query using Except might be a better choice. (Here is a link to the supported Set extensions in LINQ to Entities)

   var exceptionList = myEntities.MyOtherEntity
                                 .Select(e => e.Name);

   var query = myEntities.MyEntity
                         .Select(e => e.Name)
                         .Except(exceptionList);

This assumes a complex entity in which you are excluding certain ones depending some property of another table and want the names of the entities that are not excluded. If you wanted the entire entity, then you'd need to construct the exceptions as instances of the entity class such that they would satisfy the default equality operator (see docs).

Using 'NOT IN' Clause in LINQ Query

You should've done it the other way around. Call Contains() on the subquery, the one that has multiple items in it :

!(from t2 in db.ASN_ITEM
  where t2.SCAN_STAT != 2
  select t2.AWB_NO
).Distinct()
 .Contains(t.AWB_NO)

Also, you have to select AWB_NO directly, as shown above, instead of projecting to anonymous type. Doing the latter will prevent usage of Contains(), since item type in collection will be different from object type passed as parameter of Contains().

NOT IN Condition in Linq

Except expects argument of type IEnumerable<T>, not T, so it should be something like

_empIds = _cmn.GetEmployeeCenterWise(_loggedUserId)                              
                           .Select(e => e.Id)
                           .Except(new[] {_loggedUserId}) 
                           .ToList();

Also note, this is really redundant in the case when exclusion list contains only one item and can be replaces with something like .Where(x => x != _loggedUserId)

how to use Linq NOT IN

var _result = from a in tblContractor
              where !(from b in tbSiteByCont
                        where FKSiteID  == 13
                        select b.FKConID)
                        .Contains(a.PKConID)
              select a;

or

var siteLst = tbSiteByCont.Where(y => y.FKSiteID == 13)
                          .Select(x => x.FKConID);
var _result = tblContractor.Where(x => !siteLst.Contains(x.PKConID));

Trouble converting a Query Syntax LINQ query using a 'not in (subquery)' into Method Syntax

All you need to do is to call the .Contains method on your subquery, just like in the query syntax:

Foo = await _context.foo
    .Where(r => r.pid == PId)
    .Where(r => !DraftStatusExceptionList.Contains(r.Stat))
    .Where(r => r.Csstat != "UNK" || !String.IsNullOrEmpty(r.Csstat))
    .Where(r => !_context.foo
        .Where(rr => rr.pid == PId)
        .Select(rr => rr.fooId)
        .Contains(r.fooId))
    .OrderBy(r => r.Sdate)
    .ThenBy(r => r.Sdate2)
    .ThenBy(r => r.recordlocator)
    .ToListAsync();

In the last Where method call, you're pulling out from the database some fooIds that match the condition into a new collection, and then check your main collection's element against it.

Note the new variable name rr used in the subquery to distinguish elements in the query and subquery, and the negation of .Contains method result.

Edit: slight code corrections and adding ordering method calls.

How to make select not in clause using linq sql

TOP makes no sense without an ORDER BY.

Assuming you're paging the results sorted by the customer ID, try:

List<Customer> page = context.Customers
    .OrderBy(c => c.CustomerID)
    .Skip(3).Take(3)
    .ToList();

Linq NOT IN query - based on SQL query

The rough equivalent of a (not) in is using Contains(). Since the inner subquery doesn't reference the outer, you could write it like this:

var completedIds =
    (from r in ctx.References
    where r.Status == "COMPLETED"
    select r.Id).Distinct();

var count =
    (from r in ctx.References
    where !completedIds.Contains(r.ID)
    where r.Status == "FAILED"
    select r.Id).Distinct().Count();

Sql Query with not in clause of subquery to LINQ query

This

    from a in user_user_connection 
    join b in user_user_connection on 
        new {From=a.userid_to, To=a.userid_from} equals new {From=b.userid_from, To=b.userid_to} into c
    from d in c.DefaultIfEmpty()
    where d == null
    select a;

is similar to

select a.*
from user_user_connection a
left join user_user_connection b on a.userid_to = b.userid_from and a.userid_from = b.userid_to
where b.userid_from is null

which should match your not in query.

if you want a specific userid_from you can add another where

    from a in user_user_connection 
    where a.userid_from == 3464
    join b in user_user_connection on 
        new {From=a.userid_to, To=a.userid_from} equals new {From=b.userid_from, To=b.userid_to} into c
    from d in c.DefaultIfEmpty()
    where d == null
    select a;

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