Question

我有一个查询，我必须加入2表，如何简化以下查询

这是组织表结构

table : organizations

 id name
   1   A
   2   B
   3   C
   4   D

这是org_mapping表结构

table : org_mapping  mapping table structure

 id org_id service_provider_id
  1  1                      2
  2  4                      1


SELECT om.service_provider_id AS associated_with,
       o.name,
       o.logo,
       o.is_active            AS active
FROM   org_mapping om
       LEFT JOIN organizations o
              ON om.service_provider_id = o.id
WHERE  org_id = ?
       AND o.is_active = 1
UNION ALL
SELECT om.org_id   AS associated_with,
       o.name,
       o.logo,
       o.is_active AS active
FROM   org_mapping om
       LEFT JOIN organizations o
              ON om.org_id = o.id
WHERE  service_provider_id = ?
       AND o.is_active = 1

有什么我可以在工会之外加入，

如果我给2，我希望输出为组织1和4

Answer 1

这取决于您希望以另一种方式查看结果

Left Join organizations表两次获得结果，但数据将并排显示，UNION将数据一个接一个地放置

SELECT om.service_provider_id AS associated_with,
       o.name,
       o1.name
FROM   org_mapping om
       LEFT JOIN organizations o
              ON om.service_provider_id = o.id
       LEFT JOIN organizations o1
              ON om.org_id = o1.id

如何简单地解决这个SQL查询问题

1 个答案: