使用实体框架和LINQ未知列错误 [英] Unknown column error using Entity Framework and LINQ

问题描述

我开始与EF昨天和我在急难将这一简单的查询到EF sintax

翻译：

 从报价o选择a.city，解决，offer_address OA
其中，o.identifier = oa.offeridentifier
和a.identifier = oa.addressidentifier
按a.city
为了通过COUNT（*）说明
 

进入：

  VAR城市=（邻在db.offer
              从在db.address
              从OA在db.offer_address
              其中，（o.identifier == oa.offeridentifier
                  ＆功放;＆安培; a.identifier == oa.addressidentifier）
              一组由a.city成C
              选择新
              {
                  量= c.Count（），
                  城市= c.Key
              }）OrderByDescending（一个=＆GT; a.quantity）。选择（一个=＆GT; a.city）;

VAR cityCollection =新的名单，其中，串＆GT;（）;
的foreach（在城市VAR市）
    city​​Collection.Add（city.ToString（））;
 

我已经试过withou成功

  VAR城市=（从OA在db.offer_address
                    从在db.offer.Where（X =＆GT; x.identifier == oa.identifier）
                    从广告中db.address.Where（Y =＆GT; y.identifier == oa.offeridentifier）.AsEnumerable（）
                通过新的{ad.city}组ad.city为G
                选择新
                {
                    量= g.Count（），
                    城市= g.Key
                }）OrderByDescending（一个=＆GT; a.quantity）;
 

发生在尝试获得第一循环中的问题！

 未知列'GroupBy1.K1在字段list'`

第55行：的foreach（在城市VAR市）`
 

对于第二种情况：

无法小组A1

更新

这code的作品，但它不是我需要

  VAR城市=（
                    从db.offer的
                    从广告中db.address
                    从OA在db.offer_address
                    其中，（of.identifier == oa.offeridentifier和放大器;＆安培; ad.identifier == oa.addressidentifier）
                通过新的{ad.city}组ad.city为G
                选择新
                {
                    量= g.Count（）
                }）OrderByDescending（一个=＆GT; a.quantity）
 

或

  VAR城市=（
                    从db.offer的
                    从广告中db.address
                    从OA在db.offer_address
                    其中，（of.identifier == oa.offeridentifier和放大器;＆安培; ad.identifier == oa.addressidentifier）
                通过新的{ad.city}组ad.city为G
                选择新
                {
                    城市= g.Key
                }）;
 

解决方案

更​​新 - 尝试添加​​ AsEnumerable（）后的第一个选择

  VAR的查询=（邻在db.offer
            从在db.address
            从OA在db.offer_address
            其中，（o.identifier == oa.offeridentifier和放大器;＆安培; a.identifier == oa.addressidentifier）
            一组由a.city成C
            选择新
            {
               量= c.Count（），
               城市= c.Key
            }）
            .AsEnumerable（）
            .OrderByDescending（一个=＆GT; a.quantity）
            。选择（一个=＆GT; a.city）;
 

I started with EF yesterday and I am in trouble to transform this simple query into EF sintax

Translate:

select a.city from offer o, address a, offer_address oa
where o.identifier = oa.offeridentifier 
and a.identifier = oa.addressidentifier
group by a.city
order by count(*) desc

Into:

var cities = (from o in db.offer
              from a in db.address
              from oa in db.offer_address
              where (o.identifier == oa.offeridentifier
                  && a.identifier == oa.addressidentifier)
              group a by a.city into c
              select new
              {
                  quantity = c.Count(),
                  city = c.Key
              }).OrderByDescending(a => a.quantity).Select(a => a.city);

var cityCollection = new List<string>();
foreach (var city in cities)
    cityCollection.Add(city.ToString());

I have tried withou success

var cities = (from oa in db.offer_address
                    from of in db.offer.Where(x => x.identifier == oa.identifier)
                    from ad in db.address.Where(y => y.identifier == oa.offeridentifier).AsEnumerable()
                group ad.city by new { ad.city } into g
                select new
                {
                    quantity = g.Count(),
                    city = g.Key
                }).OrderByDescending(a => a.quantity);

The problem occurs when try to get inside the first loop!

Unknown column 'GroupBy1.K1' in 'field list'`

Line 55: foreach (var city in cities)`

With the second case:

Can't group on 'A1'

UPDATE

This code works, but its not i need

var cities = (
                    from of in db.offer
                    from ad in db.address
                    from oa in db.offer_address
                    where (of.identifier == oa.offeridentifier && ad.identifier == oa.addressidentifier)
                group ad.city by new { ad.city } into g
                select new
                {
                    quantity = g.Count()
                }).OrderByDescending(a => a.quantity)

Or

var cities = (
                    from of in db.offer
                    from ad in db.address
                    from oa in db.offer_address
                    where (of.identifier == oa.offeridentifier && ad.identifier == oa.addressidentifier)
                group ad.city by new { ad.city } into g
                select new
                {
                    city = g.Key
                });

解决方案

Update - Try adding AsEnumerable() after the first select

var query = (from o in db.offer
            from a in db.address
            from oa in db.offer_address
            where (o.identifier == oa.offeridentifier && a.identifier == oa.addressidentifier)
            group a by a.city into c
            select new
            {
               quantity = c.Count(),
               city = c.Key
            })
            .AsEnumerable()
            .OrderByDescending(a => a.quantity)
            .Select(a => a.city);

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