Question

我想将此代码转换为linq：

select t1.title, COUNT(*)as num 
from t1 INNER join t2 on t2.gId = t1.Id 
group by t1.title, t1.cId 
having t1.cId = 2

我在下面尝试了以下代码：

from p in db.t1s join r in db.t2s on p.Id equals r.gId 
where p.cId == 2 
group p by p.title into g 
select new{ name = from o in g select o.title, num = g.Count()}

但这不会正确返回COUNT。

请指导我如何解决问题

感谢

Answer 1

如果没有样本数据，很难做到正确，但请尝试使用此代码段

from p in db.t1s 
join r in db.t2s on p.Id equals r.gId 
where p.cId == 2 
group p by new {p.title, p.cId} into grouped
select new{ name = grouped.Key.title, num = grouped.Count()}

另外，请注意这个sql：

select t1.title, COUNT(*)as num 
from t1 INNER join t2 on t2.gId = t1.Id 
group by t1.title, t1.cId 
having t1.cId = 2

由于COUNT（*），将始终返回1。原因是您已经过滤t1.cId = 2并将t1.cId分组为第二个参数。

linq中的GROUP BY和HAVING

1 个答案: