[从一个表中选择金额，按

Question

我想通过CustomerID，Category，Store和City选择金额。

如果可以，请更正此查询？

var query = db.Amounts.Where(x => x.CustomerID == Convert.ToInt32(lkpCustomer.EditValue) &&
                  x.CatagoryID == Convert.ToInt32(lkp_Catagory.EditValue) && x.StoresID == Convert.ToInt32(lkp_from.EditValue) &&
                  x.CityID == Convert.ToInt32(lkp_to.EditValue)).Select(x => x.Amount1).ToList();
RateSpinEdit.EditValue = query;

说明：

Answer 1

如果我没记错的话，您需要根据以下字段将amount列的值分组：

[CustomerID，Category，Store和City。

在这种情况下，以下代码可能是您的问题的答案：

var query = (from p in Amounts
         group p by new { p.CustomerID, p.CatagoryID, p.StoresID, p.CityID}
         into grp
         where 
         (
            p => p.CustomerID    == Convert.ToInt32(lkpCustomer.EditValue) &&
                 p.CatagoryID    == Convert.ToInt32(lkp_Catagory.EditValue) &&
                 p.StoresID      == Convert.ToInt32(lkp_from.EditValue) &&
                 p.CityID        == Convert.ToInt32(lkp_to.EditValue)            
         )
         select new 
         {
                grp.key.ID,
                grp.key.CategoryID,
                grp.key.CustomerID,
                grp.key.StoresID,
                grp.key.CityID,
                SumOfAmount = grp.Sum(p => p.Amounts)            
         }).ToList();

Answer 2

谢谢大家的帮助。我使用此代码，它成功完成工作：

使用（var db = new dbDataContext（））{var datasource = db.amounts;

            var query = from amount in datasource
                        where amount.CatagoryID == Convert.ToInt32(lkp_Catagory.EditValue)&&
                        amount.CustomerID == Convert.ToInt32(lkpCustomer.EditValue)&&
                        amount.StoresID == Convert.ToInt32(lkp_from.EditValue)&&
                        amount.CityID == Convert.ToInt32(lkp_to.EditValue)
                        select amount;
            RateSpinEdit.EditValue = query.Select(x => x.Amount1).FirstOrDefault();