实体框架 - Linq NOT IN查询

Question

I've seen several other posts asking similar question but frankly I'm confused. I'm trying to do the following sql statement in EntityFarmework and Linq but cant get the 'NOT IN' and 'UNION' working

SELECT LmsTeam.* FROM LmsTeam
INNER JOIN Game ON LmsTeam.GameId = Game.ID 
WHERE LmsTeam.Id NOT IN 
(SELECT TeamHomeId as TeamID FROM LmsEventMatch WHERE EventId =1
UNION
SELECT TeamAwayId as TeamID FROM LmsEventMatch WHERE EventId =1)
AND LmsTeam.GameId = 1 AND LmsTeam.Active = 1

So I've got the join and some of the where clause as below but can't do the NOT IN and UNION clauses.

from t in LmsTeams
join g in Games on t.GameId equals g.Id
  where t.GameId == 1 && t.Active == true
  select t

Answer 1

How about that:

from t in LmsTeams
join g in Games on t.GameId equals g.Id
where t.GameId == 1 && t.Active == true && !(
        (from m in LmsEventMatch where m.EventId == 1 select m.TeamHomeId).Union(
         from m in LmsEventMatch where m.EventId == 1 select m.TeamAwayId)
    ).Contains(t.Id)
select t

I haven't tested it because don't have your data context, but think it should be done that way.

Update

I think you can avoid Union here:

from t in LmsTeams
join g in Games on t.GameId equals g.Id
where t.GameId == 1 && t.Active == true && !(
        LmsEventMatch.Where(m => m.EventId == 1).SelectMany(m => new int[] { m.TeamHomeId, TeamAwayId })
    ).Contains(t.Id)
select t

Answer 2

Another solution is to use Left outer join and keep the records where joined columns are null.

An example is given below:

var query = db.Categories    
  .GroupJoin(db.Products,
      Category => Category.CategoryId,
      Product => Product.CategoryId,
      (x, y) => new { Category = x, Products = y })
  .SelectMany(
      xy => xy.Products.DefaultIfEmpty(),
      (x, y) => new { Category = x.Category, Product = y })
  .Where(w => w.Product.CategoryId == null)
  .Select(s => new { Category = s.Category});

Answer 3

you can write and divide you query as below that will resolve your issue easily.

Also check my post : SQL to LINQ ( Case 7 - Filter data by using IN and NOT IN clause)

//first do the union of two
var query = ((from d in  LmsEventMatch 
             where d.EventId == 1
              select d.TeamHomeId).
        Union(from e in  LmsEventMatch 
                       where e.EventId == 1
                          select e.TeamAwayId));

//than perform !contains operation for no in
var records =( from t in LmsTeams
join g in Games on t.GameId equals g.Id
  where t.GameId == 1 && t.Active == true && !query.Contains(t.Id)
  select t).ToList();

graphical representation of in and not in - linq query

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for conversion from sql to linq you can use : Linqer

Answer 4

var homeIds = LmsEventMatch.Where(em => em.Eventid == 1)
                           .Select(em => em.TeamHomeId);
var awayIds = LmsEventMatch.Where(em => em.Eventid == 1)
                           .Select(em => em.TeamAwayId);
var allIds = homeIds.Union(awayIds);

var query = LmsTeams.Where( 
                t => !allIds.Contains( t.Id ) && t.Active == 1 && t.GameId == 1);