ネストされた選択クエリ - mysql sakilaデータベース

Question

各地区の最小の郵便番号を見つけましたが、これらの地区の郵便番号のすべての最小値の最大値を探したいと思っています。他の部分を守っている間に最大を行う方法についているIm。

select 
    district, 
    postal_code, 
    min(postal_code) from address 
group by district 
having district is not null and district !="" and postal_code>0 
order by district; 

Answer 1

のみmax(min_postal_code)は、次の文を使用し、必要な場合。

select max(min_postal_code) 
from (
    select district, min(postal_code) AS min_postal_code 
    from address 
    where district is not null and district !="" and postal_code>0 
    group by district 
    order by district) t 

MAX(min_postal_code)の地区名も必要な場合。次のステートメントを使用します。

select * 
from (select district, min(postal_code) AS min_postal_code 
    from address 
    where district is not null and district !="" and postal_code>0 
    group by district) t 
where t.min_postal_code = 
(
    select max(min_postal_code) 
    from (select district, min(postal_code) AS min_postal_code 
     from address 
     where district is not null and district !="" and postal_code>0 
     group by district) t2 
);