Question

我想知道表TRANSPORTARCHIVE每月有多少不同的TRANSPORTNO。可能有更好的方法来做到这一点。



select COUNT(distinct TRANSPORTNO)

from TRANSPORTARCHIVE 

where DATEASKED between '2015-01-01' and '2015-01-31'


select COUNT(distinct TRANSPORTNO)

from TRANSPORTARCHIVE

where DATEASKED between '2015-02-01' and '2015-02-28'


select COUNT(distinct TRANSPORTNO)

from TRANSPORTARCHIVE

where DATEASKED between '2015-03-01' and '2015-03-31'

依旧......

我想要一个输出显示12列，每个月有不同的TRANSPORTNO数

由于

Answer 1

试试这个：

select 
   COUNT(distinct TRANSPORTNO) as cnt,
   month(DATEASKED) as date_month
from TRANSPORTARCHIVE
group by month(DATEASKED)
where DATEASKED between '2015-01-01' and '2015-01-31';

Answer 2

您希望按月分组。在MySQL中有类似的东西：

select
    EXTRACT(year from DATEASKED) 
    , EXTRACT(month from DATEASKED) 
    , COUNT(distinct TRANSPORTNO)
from 
    TRANSPORTARCHIVE
where 
    DATEASKED between '2015-01-01' and '2015-03-31'
group by 
    1,2

如果您正在使用SQL Server：

select
    YEAR(DATEASKED) 
    , MONTH(DATEASKED) 
    , COUNT(distinct TRANSPORTNO)
from 
    TRANSPORTARCHIVE
where 
    DATEASKED between '2015-01-01' and '2015-03-31'
group by 1,2

Answer 3

Aleksey的答案基本上是正确的，除非你需要摆脱WHERE子句。

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如何在SQL中的一个查询中显示具有不同条件的多列？

3 个答案: