Question

有我有这张桌子＆＃39;客户＆＃39;那种自我参照。该表看起来像这样

customer
---------
id_cus    name     sex      id_cus_family    family_as
001       A        M        002              son
002       B        F        001              mother
003       C        M        002              husband
004       D        M        003              father

id_cus_family参考id_cus。我试图查询显示所有条目，并将其姓氏的名称添加为新列。我用过这个：

SELECT
  c1.* , c2.name AS family_name 
FROM 
    customer c1
    inner join customer c2 on c2.id_cus = c1.id_cus_family

但结果并未显示来自客户表的所有条目。结果如下：

query result
---------
id_cus    name     sex      id_cus_family    family_as   family_name
001       A        M        002              son         B
002       B        F        001              mother      A
002       B        F        001              mother      C
003       C        M        003              husband     D

它应该显示所有结果，对吧？或者我的查询代码有问题？我非常感谢你的帮助。

Answer 1

我修改了您的查询：

SELECT c1.*,c2.name as family_name 
FROM Customer as c1  
JOIN Customer as c2 ON c1.id_cus_family=c2.id_cus

结果如下：

id_cus  name    sex id_cus_family   family_as   family_name
1        A      M    2                son       B
2        B      F    1                mother    A
3        C      M    2                husband   B
4        D      M    3                father    C

Answer 2

您可以使用Left outer join

SELECT
    c1.* , c2.name AS family_name 
FROM 
    customer c1
left outer join customer c2
    on c2.id_cus = c1.id_cus_family

SQL自引用连接查询未显示所有条目

2 个答案: