PostgreSQL在组上删除null

我在Postgres中有一个问题：

select gender, avg(x) from db where degree = 'NO' group by gender order by gender

由于x列中的某些数据为NAN。group by的结果如下所示：

'Female','0.12107496463932107496'
'Male','0.09531828898619063658'
 null,'0.10851773264625644135'

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如何排除最后一行？空值

添加条件

性别不为空

select gender, avg(x) 
from db where degree = 'NO' and gender is not null
group by gender order by gender

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我不认为它缺少x值，我认为它缺少性别

select gender, avg(x) from db where degree = 'NO' and gender is not null group by gender order by gender