c# - 具有联接和计数的快速linq查询

如果从Jobs表包含超过200万条记录的Oracle数据库中的TOAD执行，我有这个SQL查询工具正在快速运行。

select * from Technicians  A
left join
  (select TechnicianCode,count(*)JobCount from Jobs
   where TxnCode in ('Jc','Jcd') group by TechnicianCode) B
on B.TechnicianCode =A.TechnicianCode

无法将其有效转换为linq。
有人可以帮忙吗？

最佳答案

你可以试试这个

var txnDetails =  from job in jobs
                  where job.TxnCode == "Jc" || job.TxnCode == "Jcd"
                  group job by job.TechnicianCode into g
                  select new { TechnicianCode = g.Key, count = g.Count() };

然后您可以使用join进行常规选择

 from technician in Technicians
 join txn in txnDetails on technician.TechnicianCode equals
   txn.TechnicianCode into tg
 from t in tg.DefaultIfEmpty()
 select new {Count = t==null? 0: t.count, ...}

关于c# - 具有联接和计数的快速linq查询，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/44404434/