从控制台编辑Firebase文件元数据(Edit Firebase Files Metadata From The Console)

 我宁愿按照以下方式简化它 
 
(from at in address_types
join a in address 
on at.addresstype  equals a.addresstype  into tt
from ar in tt.DefaultIfEmpty()
where (ar != null && ar.addressid == 24)
select new 
 {
    at.Description,
    ar.Address1, 
    ar.Address2, 
    ar.City 
  })
 
 我们不需要这个检查“（ja == null）”的原因是因为我们已经在这行“where（ar！= null && ar.addressid == 24）”中限制了我们的集合。 
 
 同时这个查询有效，我的POV是在SQL查询中LEFT JOIN也是多余的。 由于您的条件“a.addressid = 24”，您将不会获得NULL行，因此可以将SQL重写为INNER JOIN和LINQ查询以及 
 
(from at in address_types
    join a in address 
    on at.addresstype  equals a.addresstype
    where at.addressid == 24
    select new 
     {
        at.Description,
        a.Address1, 
        a.Address2, 
        a.City  
      })

I would rather simplify it in following way
 
(from at in address_types
join a in address 
on at.addresstype  equals a.addresstype  into tt
from ar in tt.DefaultIfEmpty()
where (ar != null && ar.addressid == 24)
select new 
 {
    at.Description,
    ar.Address1, 
    ar.Address2, 
    ar.City 
  })
 
The reason why we don't need this check "(ja == null)" is because we already restricted our set in this line "where (ar != null && ar.addressid == 24)".
 
Meanwhile this query works, my POV is that LEFT JOIN is also redundant here in the SQL query. You will not get NULL rows due to your condition "a.addressid = 24" so SQL can be rewritten to INNER JOIN and LINQ query as well to
 
(from at in address_types
    join a in address 
    on at.addresstype  equals a.addresstype
    where at.addressid == 24
    select new 
     {
        at.Description,
        a.Address1, 
        a.Address2, 
        a.City  
      })