Mysql 如何进行此查询

如何进行此查询。我需要在一行中显示学生数据和家长信息。这就是问题所在

select da.nombre, da.apPaterno, da.apMaterno, f.nombre, f.aPaterno,
f.aMaterno, f.parentesco , fa.nombre, fa.aPaterno, fa.parentesco from 
datoaspirante as da
left join familiar as f on da.familiarid = f.datoaspirante
left join familiar as fa on da.familiarid = fa.datoaspirante
where fa.parentesco = 'Madre' and f.parentesco = 'Padre';

但是这个查询只显示有父亲和母亲的学生，我需要显示只有父亲或母亲的学生，或者没有父母的学生

这是学生表：

这是父表：

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由于您没有提到示例数据，我只是假设这是您想要的

select d.*,f.*
,case 
    when f.datoaspirante is null 
    then 'No parents'
    else 'Single parent'
end as type
from 
datoaspirante d
left join 
(select datoaspirante from familiar
group by datoaspirante
having count(*)<2
) f
on d.familiarid = f.datoaspirante

SELECT da.nombre, da.apPaterno, da.apMaterno, f.nombre, f.aPaterno,
f.aMaterno, f.parentesco, fa.nombre, fa.aPaterno, fa.parentesco
FROM 
datoaspirante AS da
LEFT JOIN familiar AS f ON da.familiarid = f.datoaspirante and f.parentesco = 'Padre'
LEFT JOIN familiar AS fa ON da.familiarid = fa.datoaspirante and fa.parentesco = 'Madre';

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您将筛选出所有未设置父和母的空行，其中fa.parentesco='Madre'和f.parentesco='Padre'

将条件移动到联接时，应获得所需的行为

select d.*,f.*
,case 
    when f.datoaspirante is null 
    then 'No parents'
    else 'Single parent'
end as type
from 
datoaspirante d
left join 
(select datoaspirante from familiar
group by datoaspirante
having count(*)<2
) f
on d.familiarid = f.datoaspirante

SELECT da.nombre, da.apPaterno, da.apMaterno, f.nombre, f.aPaterno,
f.aMaterno, f.parentesco, fa.nombre, fa.aPaterno, fa.parentesco
FROM 
datoaspirante AS da
LEFT JOIN familiar AS f ON da.familiarid = f.datoaspirante and f.parentesco = 'Padre'
LEFT JOIN familiar AS fa ON da.familiarid = fa.datoaspirante and fa.parentesco = 'Madre';

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给出两个表的示例数据以及基于此的预期输出。