Linq to SQL，在 where 子句中包含重复值

Question

I have a simple table of items, called "ITEMS":

id  description
--  -----------
 1  Something
 2  Another thing
 3  Best thing

I have a list of Int32 which are item IDs I'd like to show:

List<Int32> currentItemsCodes = new List<int>();

For this example currentItemsCodes contains 1,2,2,3

Currently I have this Linq-to-SQL:

var itemDescriptions = (from a in db.ITEMS
where currentItemsCodes.Contains(a.id)
select new {a.id, a.description});

What this returns is:

1,Something
2,Another thing
3,Best thing

I need to return two "Another things":

1,Something
2,Another thing
2,Another thing
3,Best thing

Or if currentItemsCodes was 3,3,3,3 I would need 4 x "Best thing" returned

Answer 1

You should do a inner join in linq to get what you are looking for. Use the below linq query to do that.

   var itemDescriptions = (from a in db.ITEMS
            join c in currentItemsCodes
                on a.id equals c
            select new {a.id, a.description});

Answer 2

You can use a join clause for that:

var itemDescriptions = (from item in db.ITEMS
                       join i in currentItemsCodes on item.id equals i
                       select new
                       {
                           id = item.id,
                           description = item.description
                       }).ToList();

Answer 3

Something like this?

var x = db.items;
var itemDescriptions = (from a in currentItemsCodes
select new {a, x[a].description});

As in Kris's comments substitute for [a] a method to access the items by id