T-SQL: Sorting by date, then grouping?
Let's say I have a database table that looks like this:
ID name salary start_date city region
----------- ---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 R开发者_C百科obert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
Is there an easy to sort this by start_date descending, then for the each city group them by the latest start_date? For example:
ID name salary start_date city region
----------- ---------- ----------- ----------------------- ---------- ------
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
1 Jason 40420 1994-02-01 00:00:00.000 New York W
Thank you for your replies.
In SQL Server 2005 or newer could be like:
select
*
from
(select *,max(start_date) over(partition by city) max_date from tablename) alias
order by max_date desc, start_date desc
SELECT yourTable.*
FROM yourTable INNER JOIN
(SELECT city, MAX(start_date) AS max_city_date
FROM yourTable
GROUP BY city) max_dates
ON yourTable.city = max_dates.city
ORDER BY max_dates.max_city_date DESC, yourTable.city, yourTable.start_date DESC
The yourTable.city
in the ORDER BY
clause ensures a consistent grouping by city if two cities have the same max_city_date.
Join the query on itself, and group by city name. Then you can use the maximum start date for a city in the ORDER BY clause.
select c1.*
from cities c1
left join cities c2 on c1.city = c2.city
group by c1.id, c1.name, c1.salary, c1.start_date, c1.city, c1.region
order by max(c2.start_date) desc, c1.city, c1.start_date desc
The question is not clear... but this would produce the table you listed:
select *
from MyTable p
order by
(SELECT MAX(start_date) AS max_city_date FROM MyTable WHERE city=p.city) desc,
city,
start_date desc
Is that what you want?? Give me some more pointers if you can.
ID name salary start_date city region
----------- ---------- ----------- ----------------------- ---------- ----------
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
7 Alison 90620 2000-08-07 00:00:00.000 NewYork W
4 Linda 40620 1997-11-04 00:00:00.000 NewYork N
1 Jason 40420 1994-02-01 00:00:00.000 NewYork W
Try this:
SELECT *
FROM
(
SELECT
*,
(SELECT MAX(start_date) FROM cities c2 WHERE c1.city = c2.city) AS latest_start_date
FROM cities c1
)
ORDER BY latest_start_date DESC, start_date DESC
The inner query will give you something like this:
ID name salary start_date city region lastest_start_date
----------- ---------- ----------- ----------------------- ---------- ------ -------------------
1 Jason 40420 1994-02-01 00:00:00.000 New York W 2000-08-07 00:00:00.000
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N 2001-07-08 00:00:00.000
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W 2002-06-09 00:00:00.000
4 Linda 40620 1997-11-04 00:00:00.000 New York N 2000-08-07 00:00:00.000
5 David 80026 1998-10-05 00:00:00.000 Vancouver W 2001-07-08 00:00:00.000
6 James 70060 1999-09-06 00:00:00.000 Toronto N 2002-06-09 00:00:00.000
7 Alison 90620 2000-08-07 00:00:00.000 New York W 2000-08-07 00:00:00.000
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N 2001-07-08 00:00:00.000
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W 2002-06-09 00:00:00.000
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