如何将此sql转换为linq查询

本文关键字：linq 查询 转换 sql | 更新日期: 2023-09-27 18:13:30

如何将以下查询转换为linq to sql查询?

    select 
invoice.id, web_users.id, web_users.first_name, web_users.last_name,web_users.email_address 
from attendees,web_users
join invoice where attendees.invoice_id=invoice.id and invoice.seminar_id=6 and attendees.web_user_id=web_users.id

这是我所拥有的，但是它抛出了一个错误:

from att in context.Attendees
                          from webUsers in context.WebUsers
                          join invoice in context.Invoice
                          on att.InvoiceID equals invoice.ID                          
                          where invoice.SeminarID == seminarId &&
                          webUsers.ID == att.WebUserID                                       
                          select new
                          {
                              webUsers.FirstName,
                              att.InvoiceID                                                       
                          };

如何将此sql转换为linq查询

尝试:

from att in context.Attendees
                          join webUsers in context.WebUsers
on att.web_user_id equals webUsers.id
                          join invoice in context.Invoice
                          on att.InvoiceID equals invoice.ID                          
                          where invoice.SeminarID == seminarId                                       
                          select new
                          {
                              webUsers.FirstName,
                              att.InvoiceID                                                       
                          };

首先清理SQL。不要在查询中混合使用连接和隐式连接，对两者都使用显式连接:

select invoice.id, web_users.id, web_users.first_name, web_users.last_name,web_users.email_address 
from attendees
inner join web_users on web_users.id = attendees.web_user_id
inner join invoice on invoice.id = attendees.invoice_id
where invoice.seminar_id = 6

现在我认为它翻译成:

from att in context.Attendees
join webUsers in context.WebUsers on webUsers.ID equals att.WebUserID
join invoice in context.Invoice on att.InvoiceID equals invoice.ID
where invoice.SeminarID == seminarId
select new {
  webUsers.FirstName,
  att.InvoiceID                                                       
};
相关文章：