oracle sql如何取回1行只返回结果

Question

我该如何改进这段代码。

select code,max(total) from 
(select code,count(*) from table_1 group by code) 

上面的代码，不工作，因为我试图从查询结果集上做MAX函数，但失败。

Answer 1

如果你只是想号码，然后你可以使用这个：

select max(total) 
from (
    select code, 
      count(*) as total -- you forgot the column alias here 
    from table_1 
    group by code 
) 

如果你想要的代码和数，使用以下命令：

with count_result as (
    select code, 
      count(*) as total 
    from table_1 
    group by code 
) 
select code, 
     total 
from count_result 
where total = (select max(total) from count_result);