从存储过程结果中删除重复的列行并连接其他列[重复]

Posted 2023-02-24

【中文标题】从存储过程结果中删除重复的列行并连接其他列[重复]

【英文标题】：Remove Duplicate Column Rows from Stored Procedure Result and concatenate other column [duplicate]

【发布时间】：2021-09-07 04:45:42

【问题描述】：

我有这个存储过程的代码：

BEGIN
    SELECT teams.name,
            IFNULL(users.email,'N/A') as email,
            IFNULL(users.name,'N/A') as user_name,
            IFNULL(team_user.role,'N/A') as role
    FROM teams
        LEFT JOIN team_user ON teams.id=team_user.team_id
        LEFT JOIN users ON team_user.user_id=users.id
    WHERE role is NULL
    OR role='admin';
END

我想在表格中显示存储过程的结果。以下是它显示的表格示例：

Team Name	User Name
Team1	AdminUser1ForTeam1
Team1	AdminUser2ForTeam1
Team 2	AdminUser1ForTeam1
Team3	AdminUser1ForTeam3
Team3	AdminUser2ForTeam3

这个表的问题是，如果一个团队有超过 1 个管理员，团队名称将在两个单独的行中重复。以下是我想要达到的结果：

Team Name	User Name
Team1	AdminUser1ForTeam1, AdminUser2ForTeam1
Team 2	AdminUser1ForTeam1
Team3	AdminUser1ForTeam3, AdminUser2ForTeam3

我尝试使用 group_concat 但是无法检测到团队名称何时重复。 我也可以使用php来尝试并达到结果。非常感谢任何帮助！

【参考方案1】：

使用聚合。我怀疑你真的想要：

SELECT t.name,
        COALESCE(GROUP_CONCAT(u.email), 'N/A') as email,
        COALESCE(GROUP_CONCAT(u.name), 'N/A') as user_name,
        COALESCE(GROUP_CONCAT(tu.role), 'N/A') as role
FROM teams t LEFT JOIN
     team_user tu
     ON t.id = tu.team_id AND tu.role = 'admin' LEFT JOIN
     users u
     ON tu.user_id = u.id
GROUP BY t.name