Question

select 
    t.Ticketid, t.subject, t.createdby,
    count(TicketConversationId) as counts 
from 
    dbo.ticket t 
join 
    dbo.TicketConversation tc on t.ticketid = tc.ticketid
group by 
    t.Ticketid, t.subject, t.createdby

代码：

var Result = from t1 in Tickets 
             join t2 in TicketConversations on t1.TicketId equals t2.TicketId 
             select new { t1.TicketId, t1.Subject , comments = t2.TicketConversationId };

Answer 1

好的，要为查询添加计数和分组，请使用GroupBy：

var result = from t1 in Tickets 
             join t2 in TicketConversations on t1.TicketId equals t2.TicketId 
             group t2.TicketConversationId by new { t.Ticketid, t.Subject, t.createdby } into g
             select new { 
                 t1.TicketId, 
                 t1.Subject , 
                 t1.CreatedBy, 
                 Count = g.Count() };

请注意，当您使用EF时，如果您正确定义了Navigation Properties，则无需显式编写连接，只需t1.Conversations.Count()或类似。

您只需要计算匹配的t2中的记录数，就可以使用group join

var result = from t1 in Tickets
             join t2 in TicketConversations on t1.TicketId equals t2.TicketId into con
             select new {
                 t1.TicketId,
                 t1.Subject,
                 t1.CreatedBy,
                 Count = con.Count()
             };

如何将以下SQL查询转换为C＃中的Linq查询

1 个答案: