Question

我正在制作以下格式的用户状态列表 “A喜欢B的XXX” 。 A和B都是注册用户，具有名字和姓氏以及用户ID。如何将状态表与用户表连接两次以获取两个用户的名称？谢谢。

SELECT "SQACTION"."TIMECREATED", 
       "SQWORDLIST".*, 
       "SUBJECT"."FIRSTNAME" subject_fn,
       "SUBJECT"."LASTNAME" subject_ln, 
        author.firstname author_fn, 
        author.lastname author_ln 
FROM "SQACTION" 
  INNER JOIN "SQWORDLIST"
    ON SQACTION.ACTION = SQWORDLIST.GUID 
  INNER JOIN "SQUSER" SUBJECT
    ON SQACTION.SUBJECT = SUBJECT.GUID 
  LEFT JOIN SQDOCUMENT
    ON SQACTION.ENTITY = SQDOCUMENT.GUID 
  LEFT JOIN SQUSER AUTHOR
    ON SQDOCUMENT.AUTHORID = AUTHOR.GUID 
WHERE (SUBJECT.GUID = 'B4D3BF632C0C4DB3AB01C8B284069D8F') 
   OR (SUBJECT.GUID IN ('67882AF3FA3C4254AF9A12CA0B0AB6E4',
                        '6A4B52FE233444838AACFE2AFFE4D38F',
                        '8CA3FB9061FF4710B51F1E398D3D1917')) 
ORDER BY "TIMECREATED" DESC

这是我尝试过的。谢谢。

Answer 1

您需要在FROM子句中包含两次表名，并使用别名，以便指定在ON语句中使用表的每个实例中的哪些字段。你没有在你的问题中提供足够的细节来给出一个确切的例子，所以这里有一些更通用的东西。

UserTable，ID＆amp;名称

RegTable，UserID和SponsorID

select ut1.name as [User],
       ut2.name as [Sponsor]
from   UserTable ut1
       inner join RegTable rt on ut1.id = rt.userid
       inner join UserTable ut2 on rt.sponsorid = ut2.id

Answer 2

你的意思是，status有两个到用户表的字段链接吗？

select user_a.first_name as user_a_first_name, user_b.first_name as user_b_first_name, status.status_name
from status
left join users as user_a on user_a.id = status.user_from_id 
left join users as user_b on user_b.id = status.user_to_id

SQL连接多次？

2 个答案: