mysql - 查询以获取 MySQL 中不同值的计数

Question

我已经在 MySQL 中尝试了以下查询，但没有工作。

select count(*)
from (
      select count distinct(RADL_REQUEST_MSISDN)
      from rbt_activation_details_log
      where RADL_ACTIVE ='A'
      group by RADL_REQUEST_MSISDN
     );

Answer 1

select count(distinct column_whose_distinct_values_you_want_to_count) 
from rbt_activation_details_log 
where RADL_ACTIVE ='A' 
group by RADL_REQUEST_MSISDN

您正在对同一列进行分组和计数，因此这将始终为您1提供结果。

编辑：

然后简单地省略 group by 子句

select count(distinct RADL_REQUEST_MSISDN) 
from rbt_activation_details_log 
where RADL_ACTIVE ='A' 

Answer 2

SELECT COUNT(DISTINCT RADL_REQUEST_MSISDN)
FROM rbt_activation_details_log
WHERE RADL_ACTIVE = 'A'
GROUP BY RADL_REQUEST_MSISDN;

Answer 3

SELECT Count(UNIQUE(radl_request_msisdn))
FROM   rbt_activation_details_log
WHERE  radl_active = 'A'
GROUP  BY radl_request_msisdn  

Answer 4

根据您的查询：

select count(*) 
from
    (select count distinct(RADL_REQUEST_MSISDN)
    from rbt_activation_details_log
    where RADL_ACTIVE ='A' group by RADL_REQUEST_MSISDN);

显示为您要检索未按 radl_request_msisdn 分组的所有不同计数。如果是这样，那么您以这种方式重写您的查询：

    select count distinct(RADL_REQUEST_MSISDN)
    from rbt_activation_details_log
    where RADL_ACTIVE ='A';

相反，如果您想分组，查询将是：

    select count distinct(RADL_REQUEST_MSISDN)
    from rbt_activation_details_log
    where RADL_ACTIVE ='A' group by RADL_REQUEST_MSISDN;