Question

我有一个简单的项目表，名为＆＃34; ITEMS＆＃34;：

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

我有一个Int32列表，它是项目ID我想要显示：

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

对于此示例，currentItemsCodes包含1,2,2,3

目前我有这个Linq-to-SQL：

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

返回的是：

1,Something
2,Another thing
3,Best thing

我需要返回两个＆＃34;另一个＆＃34;：

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

或者如果currentItemsCodes是3,3,3,3我需要4 x＆＃34;最好的东西＆＃34;返回

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

Linq to SQL，包含where子句重复值

3 个答案: