求一关于统计的SQL语句,想了三天了

Question

select top 1 month(dateRegistered) from Pet group by month(dateRegistered) order by count(*) desc

Answer 1

select count(dateregistered) from pet
where datepart(month,dateregistered)=1

Answer 2

SELECT MAX(MC) FROM (
SELECT MONTH(REQUIREDDATE)AS MC  FROM [NORTHWIND].[DBO].ORDERS GROUP BY MONTH(REQUIREDDATE))
A

Answer 3

select top 1  b.[date],b.[amount]
from
(
 select 
 distinct convert(char(7),a.dateRegistered,20) as [date],
 (select count(dateRegistered) from pet where datediff(year,a.dateRegistered,dateRegistered)=0 and datediff(month,a.dateRegistered,dateRegistered)=0 ) as [amount]
 from pet as a 
) b

Answer 4

应该要考虑到跨年的情况吧
select t.y,t.m from
(select y=year(dateRegistered),m=month(dateRegistered) from pet) t
group by t.y,t.m
order by count(*) desc

Answer 5

select top 1 * from 
(select count(*) as num,year(dateRegistered) as year,month(dateRegistered) as month from Pet group by year(dateRegistered),month(dateRegistered)) T
order by num DESC