C＃Linq找到重复的行

人

Name City Joe Houston Jerry London Alex Houston Jerry London 

如何使用LINQ返回重复行

SQL

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

我试了一下

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

Answer 1

你需要一个地方，而不是一个选择：

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

Answer 2

基于@Jon Skeet的回答，使用“ 单线 ”替代方案，返回重复值，而不仅仅是键：

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