Question

这是我在sql-server中的表结构：

id           Marks
----------   -----------
AAA          50
KKK          87
KKK          89
BBB          48
CCC          54
AAA          52
DDD          55
BBB          60
XXX          99

这是所需的输出：

Name       attempts         Max Mark
-------    ----------------  ------------
AAA         2                 52
kkk         2                 89
BBB         2                 60
CCC         1                 54
DDD         1                 55
XXX         1                 99

我试过这个，但似乎不对：

SELECT 
    name,
    count(*) as attempts,
    max(marks) 
FROM table_name 
GROUP BY name, attempts, max_marks

Answer 1

试试这个：

SELECT 
    id AS Name,
    count(id) AS attempts,
    max(Marks) AS Max_Mark
FROM table_name 
GROUP BY id

Answer 2

你在正确的轨道上添加了太多的分组字段，

SELECT id AS name
       ,COUNT(*) AS Attempts
       ,MAX(marks) as MaxMarks
    FROM table_name
    GROUP BY id

如果您的列已经是MAX或COUNT等汇总函数的一部分，则不需要将其包含在GROUP BY子句中

如何在sql-server中编写此查询？

2 个答案: