mysql - SQL 查询返回太多结果

Question

我有一个几乎正确的 SQL 查询，但是当用户在数据库中拥有超过 1 架飞机时，他们最终会在返回的结果中出现多行列表:

SELECT  a.this_pay, 
    u.username, 
    u.user_id, 
    c.type_id,
    c.is_primary, 
    x.typename, 
    p.pf_city, 
    p.pf_state, 
    n.username AS non_username, 
    n.user_id AS non_user_id, 
    n.pf_city AS non_pf_city, 
    n.pf_state AS non_pf_state 
    FROM (((((jowner_event_attendees a 
    LEFT JOIN jowner_users u ON a.user_id = u.user_id) 
    LEFT JOIN jowner_aircraft c ON a.user_id = c.user_id) 
    LEFT JOIN jowner_aircraft_types x ON x.id = c.type_id) 
    LEFT JOIN jowner_profile_fields_data p ON a.user_id = p.user_id) 
    LEFT JOIN jowner_not_users n ON a.user_id = n.user_id) 
    WHERE a.event_id = 28 ORDER BY COALESCE(u.username,non_username);

我最终得到的列表包含多个条目，适用于拥有多架飞机的任何人，我只希望返回 1 个条目，无论他们在“jowner_aircraft”表中有多少飞机条目。

我也不想大幅更改此查询，因为应用程序的其他部分依赖它，显然它需要我要求的修订，但请尝试在不完全重写的情况下回答它。

Answer 1

SELECT  a.this_pay, 
    u.username, 
    u.user_id, 
    c.type_id, 
    x.typename, 
    p.pf_city, 
    p.pf_state, 
    n.username AS non_username, 
    n.user_id AS non_user_id, 
    n.pf_city AS non_pf_city, 
    n.pf_state AS non_pf_state 
    FROM (((((jowner_event_attendees a 
    LEFT JOIN jowner_users u ON a.user_id = u.user_id) 
    LEFT JOIN jowner_aircraft c ON a.user_id = c.user_id AND c.is_primary=1) 
    LEFT JOIN jowner_aircraft_types x ON x.id = c.type_id) 
    LEFT JOIN jowner_profile_fields_data p ON a.user_id = p.user_id) 
    LEFT JOIN jowner_not_users n ON a.user_id = n.user_id) 
    WHERE a.event_id = 28 ORDER BY COALESCE(u.username,non_username);