Question

我正在寻找输出：

|  BOOK |        ANALYST |         SUPERVISOR |
|-------|----------------|--------------------|
| BookA |         (null) |         Dani Sant  |
| BookB |         (null) |  North Andre Miles |
| BookC |    Andrea Plus |        Andrea Plus |
| BookD | Jeff Dron Math |     Jeff Dron Math |
| BookE |   Theo Phillip |       Julian Rhode |

我得到的是：

|  BOOK |        ANALYST |   SUPERVISOR |
|-------|----------------|--------------|
| BookA |         (null) |    dani.sant |
| BookB |         (null) |  north.miles |
| BookC |    Andrea Plus |  andrea.plus |
| BookD | Jeff Dron Math |    jeff.math |
| BookE |   Theo Phillip | julian.rhode |

我可以使用一列进行连接，但是当我尝试两者时，结果不会显示它应该如此。感谢您提供任何相关信息。

SQL Fiddle

MS SQL Server 2008架构设置：

CREATE TABLE books 
  (
    book varchar(10),
    analyst varchar(100),
    supervisor varchar(100)
  );

INSERT INTO books (book, analyst, supervisor)
VALUES
('BookA', NULL, 'dani.sant'),
('BookB', NULL, 'north.miles'),
('BookC', 'andrea.plus', 'andrea.plus'),
('BookD', 'jeff.math', 'jeff.math'),
('BookE', 'theo.phil', 'julian.rhode');

CREATE TABLE names 
  (
    username varchar(100),
    fullname varchar(500)
  );

INSERT INTO names (username, fullname)
VALUES
('dani.sant', 'Dani Sant'),
('north.miles', 'North Andre Miles'),
('andrea.plus', 'Andrea Plus'),
('jeff.math', 'Jeff Dron Math'),
('theo.phil', 'Theo Phillip'),
('julian.rhode', 'Julian Rhode');

查询1 ：

SELECT
    books.book AS Book,
    names.fullname AS Analyst,
    books.supervisor AS Supervisor
FROM
    books left join names on books.analyst = names.username

Results ：

|  BOOK |        ANALYST |   SUPERVISOR |
|-------|----------------|--------------|
| BookA |         (null) |    dani.sant |
| BookB |         (null) |  north.miles |
| BookC |    Andrea Plus |  andrea.plus |
| BookD | Jeff Dron Math |    jeff.math |
| BookE |   Theo Phillip | julian.rhode |

Answer 1

您需要第二个join到names表格才能获得主管的全名：

SELECT b.book AS Book, bn.fullname AS Analyst,
       sn.fullname AS Supervisor
FROM books b left join
     names bn
     on b.analyst = bn.username left join
     names sn
     on b.supervisor = sn.username;

Answer 2

下面将提供您想要的输出。

 SELECT
        b.book AS Book,
        n.fullname AS Analyst,
        (SELECT fullname FROM names where username=b.Supervisor) AS Supervisor
    FROM
        books b left join names n on b.analyst = n.username

根据2列的用户名获取全名

2 个答案: