SQL to LINQ：使用 group by、join、where with count答案

【问题标题】：SQL to LINQ: using group by, join, where with countSQL to LINQ：使用 group by、join、where with count
【发布时间】：2015-10-16 10:11:14
【问题描述】：

我有这样的 SQL：

select p.ProductID, count(pa.Value) as condition
from ProductBE as p
join ProductAttributeBE as pa 
on p.ProductID = pa.ProductID
where ProductCategoryID = 1203
and (Value = 'PassingerCar' or Value = '15')
group by p.ProductID

ProductBE 与 ProductAttributeBE 是一对多什么觉得它看起来像这样：

var query1 = from p in this.DataBase.ProductBEs
             join a in this.DataBase.ProductAttributeBEs
             on p.ProductID equals a.ProductID
             where  p.ProductCategoryID == 1203 && (a.Value == radius ||                    a.Value == carType) 
             group p by p.ProductID into grp
             select new { grp.Key, Condition = grp.Count(x => x.Value !=   null) };

此代码未编译从不同的表/别名中选择或分组时遇到问题

【问题讨论】：

标签： sql-server linq join group-by

【解决方案1】：

试试这个：

var query1 = from p in this.DataBase.ProductBEs
             join a in this.DataBase.ProductAttributeBEs
             on p.ProductID equals a.ProductID
             where  p.ProductCategoryID == 1203 && (a.Value == radius || a.Value == carType) 
             select new {p.ProductID, a.Value} into t
             group t by t.ProductID into grp
             select new { grp.Key, Condition = grp.Count(x => x.Value != null) };

【讨论】：