LINQ to SQL in和not in

Question

LINQ to SQL中有什么in和not in等于什么 ？

例如

select * from table in ( ...)
and 
select * from table not in (..)

什么等于LINQ to SQL中的上述语句？

Answer 1

你用, where <list>.Contains( <item> )

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

或者您可以预定义列表:

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

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

对于'NOT'的情况,只需添加'!' 'Contains'语句之前的运算符.

Answer 2

我对你的问题感到困惑.in并对not in查询中的字段进行操作,但您没有在示例查询中指定字段.所以它应该是这样的:

select * from table where fieldname in ('val1', 'val2')

要么

select * from table where fieldname not in (1, 2)

在LINQ to SQL中等效的那些查询将是这样的:

List<string> validValues = new List<string>() { "val1", "val2"};
var qry = from item in dataContext.TableName
          where validValues.Contains(item.FieldName)
          select item;

还有这个:

List<int> validValues = new List<int>() { 1, 2};
var qry = from item in dataContext.TableName
          where !validValues.Contains(item.FieldName)
          select item;