对同一请求使用mysql GROUP BY和ORDER BY - Using mysql GROUP BY and ORDER BY for same request

Using mysql GROUP BY and ORDER BY for same request

本文关键字：BY GROUP ORDER mysql 请求 | 更新日期: 2023-09-27

我一直在同一行中尝试GROUP BY和ORDER BY来获得我想要的东西，但它不起作用。我使用了一个while循环，它运行了数千个名字，检查每个城市的最高点。如何在不重复同一个城市两次的情况下，从每个城市获得得分最高的名字？

这就是我数据库中的内容（简而言之）：

ID City       Points    Name
1  NYC        16        Stan
2  London     24        Paul
3  NYC        11        Jeffrey
4  London     20        George
5  NYC        18        Ryan
$query = "SELECT `ID`, `City`, `Points`, `Name` FROM `table` GROUP BY `City` ORDER BY `Points`";

给我：

1 NYC 16 Stan
2 London 24 Paul

我想要它给我的：

2  London     24        Paul
5  NYC        18        Ryan

您可以使用左联接作为

select t1.* from table_name t1 
left join table_name t2 on t1.city=t2.city and t1.points < t2.points 
where t2.id is null;

或者使用不相关子查询：

select t.* from table_name t 
join ( 
  select max(points) as points,city from table_name group by city
)x on x.city=t.city and x.points = t.points ;

在此处查看文档https://dev.mysql.com/doc/refman/5.0/en/example-maximum-column-group-row.html

或子查询

select t.* from table_name t 
where not exists (
  select 1 from test t1 where t.city = t1.city and t.points < t1.points
);

这是组最大值，也是最常见的SQL问题之一。你可以试试这样的东西，

SELECT tab1.*
FROM @Table AS tab1
LEFT JOIN @Table AS tab2 
     ON tab1.City=tab2.city  AND tab2.points > tab1.points
WHERE tab2.City IS NULL;