Datediff SQL查询到Linq Lambda查询

Question

如何将此SQL函数转换为linq查询lambda表达式？

SELECT Type, DATEDIFF(day,Expiry_Date,GETDATE()) AS Days
FROM Item
GROUP BY Type, Expiry_Date;

我首先需要在数据库中创建一个函数吗？

Answer 1

这应该工作：

var result = db.Item.GroupBy(x => new { x.Type, x.ExpiryDate })
                    .Select(x => new 
                                 {
                                     Type = x.Key.Type,
                                     Days = (DateTime.Now.Date - x.Key.ExpiryDate).Days
                                 };

Answer 2

from i in db.item
group i by new{
  type = i.Type,
 eDate = i.Expiry_date
} into grp 
select new
{
 type = grp.key.Type,
 date =  grp.key.Expiry.Date.Subtract(DateTime.Now.Date).Days
}