基于列的值，LINQ删除重复 [英] Remove Duplicate based on column value-linq

问题描述

喜
我有很多员工和组之间的多对多关系。以下LINQ语句

Hi i have many to many relationship between employee and group. following linq statement

int[] GroupIDs = {6,7};


var result = from g in umGroups
    join empGroup in umEmployeeGroups on g.GroupID equals empGroup.GroupID
    where  GroupIDs.Contains(g.GroupID)                     
    select new {  GrpId = g.GroupID,EmployeeID = empGroup.EmployeeID };

收益groupId和将雇员。而结果是

returns groupid and the employeeid. and result is

GrpId  | EmployeeID
6      |   18
6      |   20  
7      |   19
7      |   20

我需要删除该雇员被重复例如行与雇员的行中的任一项= 20

感谢

I need to remove the rows for which the employeeid is repeating e.g. any one of the row with employeeid= 20
Thanks

推荐答案

好吧，如果你不在乎哪个员工被删除，你可以尝试这样的：

Okay, if you don't care which employee is removed, you could try something like:

var result = query.GroupBy(x => x.EmployeeId)
                  .Select(group => group.First());

您还没有指定这是否是LINQ to SQL中的LINQ to Objects还是其他什么东西......我不知道这个SQL转换将是什么。如果你正在处理的数据量相对较少，你可以总是强制此最后一点是在工艺：

You haven't specified whether this is in LINQ to SQL, LINQ to Objects or something else... I don't know what the SQL translation of this would be. If you're dealing with a relatively small amount of data you could always force this last bit to be in-process:

var result = query.AsEnumerable()
                  .GroupBy(x => x.EmployeeId)
                  .Select(group => group.First());

在这一点上，你可以实际使用 MoreLINQ 它有一个方便的<一个href=\"http://$c$c.google.com/p/morelinq/source/browse/MoreLinq/DistinctBy.cs\"><$c$c>DistinctBy方法：

At that point you could actually use MoreLINQ which has a handy DistinctBy method:

var result = query.AsEnumerable()
                  .DistinctBy(x => x.EmployeeId);

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