sql - SQL Select column based on Max(other column)

Question

如果我在 tblCust

c_id       Option         Numbers
10         1              2
5          1              1
10         2              1

我想返回 c_id = 10 时 Numbers 最大的选项。我试过了

 SELECT Option, MAX(Numbers) FROM tblCust WHERE c_id = 10

但没有运气

Answer 1

没有子查询，您可以对事物进行排序以获得最大的

SELECT  Option FROM tblCust
WHERE c_id = 10
ORDER BY Number DESC LIMIT 1

Answer 2

您没有指定 DBMS，所以这是标准 SQL

select *
from (
   select c_id, 
          option,
          max(option) over (partition by c_id) as max_opt
   from tblCust
   where c_id = 10
) t
where option = max_opt;

Answer 3

我认为使用 max() over() 是为了反对数字，而不是选项

select *
from (
   select c_id, 
          option,
          max(numbers) over (partition by c_id) as max_numbers
   from tblCust
   where c_id = 10
) t
where numbers = max_numbers;

但是，如果数据使得您有多个等于 max(Numbers) 的记录 - 并且您只想要一个结果记录 - 那么使用 row_number() 可能是一个更好的选择。

select *
from (
       select c_id, 
              option,
              row_number() over (partition by c_id order by Numbers DESC, Option DESC) as rn
       from tblCust
       where c_id = 10
    ) AS t
where rn=1
;

注意这里 over() 中的 order by，它首先放置最高的 Numbers 和 Option，然后将 row_number 值设为 1

Answer 4

用这个：

SELECT Option, Numbers
FROM tblCust
WHERE c_id = 10
ORDER BY Numbers DESC
LIMIT 1

输出：

Option  Numbers
1       2