Question

我有users_details表，其中包含以下列

martial_status | religion | education

我想从这个表中获取数值，如下所示。

married (100)
single (200)
Muslim(50)
Jews (50)
Christian(50)
Graduates(100) 
etc, etc.

我不知道是否可以使用单个SELECT获取所有计数，请帮忙。

Answer 1

这不是一个SELECT - 语句，但您可以使用以下一个查询检索它（假设列是兼容的）：

( SELECT `martial_status`, COUNT(*) as `cnt` FROM user_details GROUP BY `martial_status` )
UNION
( SELECT `religion`, COUNT(*) as `cnt` FROM user_details GROUP BY `religion` )
UNION
( SELECT `education `, COUNT(*) as `cnt` FROM user_details GROUP BY `education` )

Answer 2

你需要分别处理每一列，然后联合itp>

  SELECT martial_status, count(*)
  FROM USER_DETAILS
  GROUP BY martial_status
UNION ALL
  SELECT religion, count(*)
  FROM USER_DETAILS
  GROUP BY religion
UNION ALL
  SELECT education, count(*)
  FROM USER_DETAILS
  GROUP BY education

Answer 3

您可以这样做：

select sum(case when religion = 'Muslim'
           then 1
           else 0 
           end) as muslims,
       sum(case when martial_status = 'married'
           then 1
           else 0 
           end) as married
       ...
from your_table

更短的版本是：

select sum(religion = 'Muslim') as muslims,
       sum(martial_status = 'married') as married
       ...
from your_table

Answer 4

使用没有子查询或类似的单个select很棘手，但我相信单个查询也应该对您有用。您可以使用单个选择来获取给定列的所有计数，然后使用union all合并结果，以便单个查询可以获得所有列的所有计数。

select martial_status, count(*) from user_details group by martial_status
union all
select religion, count(*) from user_details group by religion
union all
select education, count(*) from user_details group by education

如果您的表中有NULL个值，您可能希望省略结果中的值。

如果它确实是你需要的单选，那么你必须改变你的表的布局，但我无法想象这种要求的正当理由。

如何从多列中获取值的计数

4 个答案: