Linq to SQL Query Using "Not In"

LINQ to SQL query using NOT IN

    List<string> states = new List<string> { "CA", "IN", "MD" };
    var q = from a in authors
            where !states.Contains(a.state)
            select new { a.au_lname, a.state };

or

   var q = authors.Where( a => !states.Contains( a.state ) )
                  .Select( a => new { a.au_lname, a.state } );

LINQ to SQL in and not in

You use, where <list>.Contains( <item> )

var myProducts = from p in db.Products
                 where productList.Contains(p.ProductID)
                 select p;

Or you can have a list predefined as such:

int[] ids = {1, 2, 3};

var query = from item in context.items
            where ids.Contains( item.id )
            select item;

For the 'NOT' case, just add the '!' operator before the 'Contains' statement.

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;

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().

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 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 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();

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).

SQL Query to LINQ syntax using not exist and join

You can try like this:

(from lk in localizationKey    
where (from l in lang
        join lv in localizationValue on l.Id equals lv.LanguageId
        where (l.Title == "en-US" && lv.LocalizationKeyId == lk.Id)   
       select l).FirstOrDefault() == null
 select lk).ToList();

or

(from lk in localizationKey    
where !(from l in lang
        join lv in localizationValue on l.Id equals lv.LanguageId
        where !(l.Title == "en-US" && lv.LocalizationKeyId == lk.Id) 
        select l).FirstOrDefault().Any()
 select lk).ToList();

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