什么是SQL查询？

Question

staff表：

      id     name
       1     tony
       2     sony
       3     bony
       4     rony
etc.

xyz表：

current staff, next staff, hod staff, vp staff.
      1          2           3          4
      2          3           1          4
      4          3           2          1
etc.

什么时候运行

`select * from xyz,`

我需要一个查询，而不是给我id它实际上是从职员表中给我该职员的名字。

Answer 1

您需要多次加入staff表

SELECT b.name AS current_staff,
       d.name AS next_staff,
       c.name AS hod_staff,
       e.name AS vp_staff
FROM   xyz a
       INNER JOIN staff b
               ON a.current_staff = b.id
       INNER JOIN staff c
               ON a.hod_staff = c.id
       INNER JOIN staff d
               ON a.next_staff = d.id
       INNER JOIN staff e
               ON a.vp_staff = e.id 

Answer 2

如果我理解正确，我想您可以在这里使用多重联接：

select a.name, b.name, c.name, d.name from xyz
        inner join staff as a on a.id = xyz.currentstaff
        inner join staff as b on b.id = xyz.nextstaff
        inner join staff as c on c.id = xyz.hodstaff
        inner join staff as d on d.id = xyz.vpstaff