Question

我的数据库中有3个表

PROJECTS
- id
- name
- date_created
- user_created
- status (or for disabled, 1 for enabled)

PROJECTS_MANAGERS (a project may have 0 or more managers)
- id
- project_id
- manager_username

PROJECTS_MEMBERS (a project may have 0 or more members)
- id
- project_id
- member_username

我正在尝试创建一个mysql连接查询，以列出特定用户所处的状态等于1的所有项目。具体来说，这个查询将列出所有项目，其中用户名为“bob”。 “use_created”，“manager_username”或“member_username”字段以及projects.status字段为1的位置。但诀窍是可能有多个管理员或成员具有相同的project_id（当然，这里有不同的ID和member_usernames）。

我已经尝试过这段代码了，但它似乎没有用（在where子句中给我错误'1054未知列'projects.status'。我试过做一个“完全加入”，但我来学习mysql不支持这个：

SELECT *
FROM
    `projects` as theProjects

LEFT OUTER JOIN
    projects_managers
            AS theManagers
                    ON theProjects.id = theManagers.project_id
WHERE
    projects.status = 1
UNION ALL

SELECT *
FROM
    `projects` as theProjects
RIGHT OUTER JOIN
    projects_members
            AS theMembers
                    ON theProjects.id = theMembers.project_id
        WHERE
    projects.status = 1

非常感谢任何帮助。

Answer 1

怎么样：

SELECT projects.*
FROM projects
LEFT JOIN projects_managers managers ON managers.project_id=projects.id
LEFT JOIN projects_members members ON members.project_id=projects.id
WHERE status=1 AND
      (user_created="bob" OR managers.username="bob" OR members.username="bob")
GROUP BY projects.id

在搜索中梳理mysql外连接

1 个答案: