Question

由于某种原因，我无法将表别名t分配给FROM子句中的第一组表。我想将此t和LEFT JOIN称为另一组表。为什么我不能这样做？

select
    job.job
from 
    (job
inner join 
    item on job.item = item.item
inner join 
    jobroute as jb on job.job = jb.job and job.suffix = jb.suffix) as t --the error message points to this line
left join 
    (select
         jb.job, jb.suffix,
         sn.notecontent
     from
         SpecificNotes as sn
     join
         ObjectNotes as onn on onn.SpecificNoteToken = sn.SpecificNoteToken
     join
         jobroute as jb on jb.RowPointer = onn.RefRowPointer) as x on t.job = x.job and t.suffix = x.suffix

Answer 1

我认为只要删除as关键字就行了。

Answer 2

括号仅用于对连接进行分组。您不会创建其他别名。

它们通常是不必要的。所以，删除它们：

outerline.beginPath();

您可能有点困惑，因为括号也用于子查询，而这些需要表别名。但是，仅仅对联接进行分组并不是别名的机会。

您还会注意到我删除了select j.job from job j join item i on j.item = i.item join jobroute jr on j.job = jr.job and j.suffix = jr.suffix left join (select jb.job, jb.suffix, sn.notecontent from SpecificNotes sn join ObjectNotes onn on onn.SpecificNoteToken = sn.SpecificNoteToken join jobroute jr on jr.RowPointer = onn.RefRowPointer ) x on t.job = j.job and t.suffix = j.suffix;。这是个人偏好。我发现as只会使as条款变得混乱，但它完全可以接受。

Answer 3

试试这个：

select
    job.job
from 
    (select
        job
    from
        job
    inner join 
         item on job.item = item.item
    inner join 
        jobroute as jb on job.job = jb.job and job.suffix = jb.suffix) as t --the error message points to this line
    left join 
    (select
         jb.job, jb.suffix,
         sn.notecontent
     from
         SpecificNotes as sn
     join
         ObjectNotes as onn on onn.SpecificNoteToken = sn.SpecificNoteToken
     join
         jobroute as jb on jb.RowPointer = onn.RefRowPointer) as x on t.job = x.job and t.suffix = x.suffix

为什么我不能在这里使用表别名？

3 个答案: