一条sql语句中的多个select

我有一个调查答案表，类似于：

date     |  q1  | q2 |
12/12/10 | yes | no | 
12/13/10 | no  | no | 

我想创建一个查询，它将获得这个表的结果摘要，允许我设置相关的日期范围。 我认为下面的陈述非常有效：

SELECT ( SELECT Count(*) 
         FROM `survey` 
         WHERE q1='Yes') AS q1_yes, 
       ( SELECT Count(*) 
         FROM `survey` 
         WHERE q1='No') AS q1_no,
       ( SELECT Count(*) 
         FROM `survey` 
         WHERE q2='Yes') AS q2_yes)

但我不确定我是否能做得更好，也不确定在哪里添加日期范围过滤。

您可以使用：

select q1, q2, count(*)
from survey
group by q1, q2

或者，如果您想得到完全相同的结果：

select count(case when q1 = 'Yes' then q1 else null end) as q1_yes,
       count(case when q1 = 'No' then q1 else null end) as q1_no,
       count(case when q2 = 'Yes' then q2 else null end) as q2_yes
from survey

您对“case”的实现可能会有所不同，重要的是您可以将所有不希望为null的内容设置为null，并且它不会被count（）计数：）

您可以使用：

select q1, q2, count(*)
from survey
group by q1, q2

或者，如果您想得到完全相同的结果：

select count(case when q1 = 'Yes' then q1 else null end) as q1_yes,
       count(case when q1 = 'No' then q1 else null end) as q1_no,
       count(case when q2 = 'Yes' then q2 else null end) as q2_yes
from survey

---

您对“case”的实现可能会有所不同，重要的是您可以将所有不希望为null的内容设置为null，并且它不会被count（）计数：）

spiny norman的第一个查询将给出如下结果：

q1    q2    count(*)
no    yes   2
yes   no    1
yes   yes   1

SELECT 'q1' as Question, s1.q1 as Answer, count(*) as Count
FROM survey s1
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q1
UNION
SELECT 'q2' as Question, q2 as Answer, count(*) as Count
FROM survey
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q2

它只对不同结果的夫妇进行分组。我假设您想按问题对“是/否”的总数进行分组。在这种情况下，您必须这样做：

q1    q2    count(*)
no    yes   2
yes   no    1
yes   yes   1

SELECT 'q1' as Question, s1.q1 as Answer, count(*) as Count
FROM survey s1
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q1
UNION
SELECT 'q2' as Question, q2 as Answer, count(*) as Count
FROM survey
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q2

---

spiny norman的第一个查询将给出如下结果：

q1    q2    count(*)
no    yes   2
yes   no    1
yes   yes   1

SELECT 'q1' as Question, s1.q1 as Answer, count(*) as Count
FROM survey s1
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q1
UNION
SELECT 'q2' as Question, q2 as Answer, count(*) as Count
FROM survey
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q2

它只对不同结果的夫妇进行分组。我假设您想按问题对“是/否”的总数进行分组。在这种情况下，您必须这样做：

q1    q2    count(*)
no    yes   2
yes   no    1
yes   yes   1

SELECT 'q1' as Question, s1.q1 as Answer, count(*) as Count
FROM survey s1
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q1
UNION
SELECT 'q2' as Question, q2 as Answer, count(*) as Count
FROM survey
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q2

---

您能指定您正在使用的服务器的类型吗？SQL Server、Oracle、MySQL等。能否指定您使用的服务器类型？SQL Server、Oracle、MySQL等。