C# 使用Linq查找重复行

人

Name        City

Joe         Houston   
Jerry       London    
Alex        Houston   
Jerry       London    

如何使用LINQ like返回重复行

Sql

SELECT name, city, count(*)
FROM collection
GROUP BY name,city 
HAVING count(*) > 1

我试过了

var qry =
    from m in context.Collections
    group m by new { m.city, m.name } into grp
    select new { rp = grp.Count() > 2 };            

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您需要的是where，而不是select：

var qry =  from m in context.Collections
           group m by new { m.city, m.name } into grp
           where grp.Count() > 1
           select grp.Key;

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以Jon Skeet的答案为基础，使用“一行”选项返回重复值，而不仅仅是键：

var duplicates = db.Collections.GroupBy(m => new { m.city, m.name })
                               .Where(a => a.Count() > 1)
                               .SelectMany(a => a.ToList());

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嗨，约翰，我想问一个问题。是否可以选择重复的行键和值？