Question

我有这个结果集：

Company_ID | State | City | Rev |
Company 1  |  S-A  |  C-1 |  1  |
Company 2  |  S-B  |  C-2 |  1  |
Company 1  |  S-A  |  C-3 |  2  |

我想要的结果集是

Company_ID | State | City | Rev |
Company 1  |  S-A  |  C-3 |  2  |
Company 2  |  S-B  |  C-2 |  1  |

以下是我尝试的查询：

var list = (from coy in TBL_COMPANY
where coy.IsActive == "1"
select coy).ToList()
.Select(coy => new 
{
  coy.Company_ID,
  coy.State,
  coy.City,
  coy.Rev
});

var companyList = list.GroupBy (grp => new
{
   grp.Company_ID,
   grp.State,
   grp.City
})
.Select(cpy => new 
{
   CompanyID = cpy.Key.Company_ID,
   State = cpy.Key.State,
   City = cpy.Key.City,
   Rev = cpy.Max(c => c.Rev)
}).ToList();

但是，我无法获得我想要的结果集。我怀疑是因为City因为它被包括在内。但是，我需要这些列（Rev除外）。有没有办法做到这一点？

Answer 1

所需的结果并不适合您的分组。有3个不同的City项目应该会产生3个结果项目。

我说Jon Skeet关于Company_ID分组的评论是正确的。

代码（按Company_ID分组并选择Rev项最高的项目：

var result = TBL_COMPANY.Where(x => x.IsActive == "1")
                        .GroupBy(x => x.Company_ID)
                        .Select(x => x.OrderByDescending(y => y.Rev).First())
                        .Select(x=> new {x.Company_ID,  x.State,  x.City,  x.Rev})
                        .ToList();

在LinQ中获取每个修订号的Max（）行

1 个答案: