Select the last entry recorded in a table for each day, within a duration of days

Question

How can I select the last entry recorded for each day? In this example, I need the last item number ordered and the last DateOrdered entry for each day over the last 5 days. Here's my table:

ItemNumber  |       DateOrdered
    1           2020-04-01 08:00:00.000
    3           2020-04-01 09:00:00.000
    5           2020-04-01 10:00:00.000
    4           2020-04-02 09:00:00.000
    6           2020-04-02 10:00:00.000
    7           2020-04-03 08:00:00.000
    3           2020-04-03 09:00:00.000
    2           2020-04-03 10:00:00.000
    5           2020-04-04 10:00:00.000
    8           2020-04-05 08:00:00.000
    2           2020-04-05 09:00:00.000
    8           2020-04-05 10:00:00.000

Here's the results I need:

ItemNumber  |      DateOrdered
    5           2020-04-01 10:00:00.000
    6           2020-04-02 10:00:00.000
    2           2020-04-03 10:00:00.000
    5           2020-04-04 10:00:00.000
    8           2020-04-05 10:00:00.000

This is as close as I can get with it:

with tempTable as
(
  select
    *,
    row_number() over(partition by datediff(d, 0, DateOrdered) order by DateOrdered desc) as rn 
  from myTable
)
select *
from tempTable  
where rn = 1

score 0 · Accepted Answer · answered Apr 14 '20 at 16:56

You are almost there. You just need to fix the definition of your partition so it puts together all rows that belong to the same day.

This should do it:

with tempTable as
(
  select
    *,
    row_number() over(partition by cast(DateOrdered as date) order by DateOrdered desc) as rn 
  from myTable
)
select *
from tempTable  
where rn = 1

Select the last entry recorded in a table for each day, within a duration of days

1 Answers1