SQL用于计算每小时的记录数，并计算总记录数大于一个值的小时数

Question

Using SQL Server 2014. I have a list of records that are time stamped and I would like to count how many records there are per hour then count how many hours each day that the record count exceeded a given number, say 20.

Here's what I have so far:

select count(distinct datepart(hour, convert(datetime, OrderStateDate))) Count_HoursOver,
    datepart(YEAR, convert(datetime, OrderStateDate)) Date_YEAR,
    datepart(month, convert(datetime, OrderStateDate)) Date_MONTH,
    datepart(day, convert(datetime, OrderStateDate)) Date_DAY
from Reporting.dbo.Orders
group by datepart(YEAR, convert(datetime, OrderStateDate)),
    datepart(month, convert(datetime, OrderStateDate)),
    datepart(day, convert(datetime, OrderStateDate))
having count(idscript) >= 20

The results aren't correct and I can't make sense of what's being returned and why. Am I using HAVING incorrectly? Any advice would be appreciated!

Answer 1

You kind of have a 2-part question here

I would like to count how many records there are per hour

You can create a query that returns tuples (RecordsPerHour,HOUR,YEAR,MONTH,DAY) as follows:

SELECT 
    count(*) as RecordsPerHour, 
    datepart(hour,convert(datetime,OrderStateDate)) as Date_HOUR, 
    datepart(year,convert(datetime,OrderStateDate)) as Date_YEAR,
    datepart(month,convert(datetime,OrderStateDate)) as Date_MONTH,
    datepart(day,convert(datetime,OrderStateDate)) as Date_DAY
FROM Reporting.dbo.Orders
GROUP BY
    datepart(year,convert(datetime,OrderStateDate)),
    datepart(month,convert(datetime,OrderStateDate)),
    datepart(day,convert(datetime,OrderStateDate)),
    datepart(hour,convert(datetime,OrderStateDate))

then count how many hours each day that the record count exceeded a given number, say 20

To do this, use the query from the first part of your question in a nested query, using a HAVING clause to filter only hours that contain at least 20 orders.

On the outer query, group by (YEAR,MONTH,DAY) to determine the number of hours in that day with at least 20 orders:

SELECT
    count(*) as HoursWithAtLeast20Orders, 
    Date_YEAR,
    Date_MONTH,
    Date_DAY
FROM
    (SELECT 
        datepart(hour,convert(datetime,OrderStateDate)) as Date_HOUR, 
        datepart(year,convert(datetime,OrderStateDate)) as Date_YEAR,
        datepart(month,convert(datetime,OrderStateDate)) as Date_MONTH,
        datepart(day,convert(datetime,OrderStateDate)) as Date_DAY
    FROM Reporting.dbo.Orders
    GROUP BY
        datepart(year,convert(datetime,OrderStateDate)),
        datepart(month,convert(datetime,OrderStateDate)),
        datepart(day,convert(datetime,OrderStateDate)),
        datepart(hour,convert(datetime,OrderStateDate))
    HAVING count(*) >=20) as t
GROUP BY
    Date_YEAR,
    Date_MONTH,
    Date_DAY

Answer 2

First round to hour then round to day

SELECT 
   count(*) as [hours with 20+ Orders],
   dateadd(day, datediff(day,'20000101',dt_hour_rounded),'20000101') as dt_day_rounded     
FROM (
   SELECT
      count(*) as OrdersInHour,
      dateadd(hour, datediff(hour,'20000101',OrderStateDate),'20000101') as dt_hour_rounded
   FROM Reporting.dbo.Orders
   GROUP BY dateadd(hour, datediff(hour,'20000101',OrderStateDate),'20000101')
) t
GROUP BY dateadd(day,datediff(day,'20000101',dt_hour_rounded),'20000101')
WHERE OrdersInHour >= 20