根据列值-linq 删除重复项 [英] Remove Duplicate based on column value-linq

问题描述

我有员工和团队之间的多对多关系.以下 linq 语句

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 };

返回 groupid 和雇员 ID.结果是

returns groupid and the employeeid. and result is

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

我需要删除员工 ID 重复的行，例如雇员id = 20的行中的任何一项
谢谢

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，如果你不在乎解雇了哪位员工，你可以试试这样的:

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());

您还没有指定这是在 LINQ to SQL、LINQ to Objects 还是其他东西中...我不知道这将是什么 SQL 翻译.如果您处理的数据量相对较少，您总是可以强制执行最后一点:

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());

那时你实际上可以使用 MoreLINQ ，它有一个方便的 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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