TSQL : the top records of a given partition (conditional) - sql

Question

I need to get all the records in TABLE_A where at least the 2 last Status are vacant (relative to Inspection_Date) and the Room_ID does not exist in TABLE_B.
This is a simplified table I am using as an example:
TABLE_A:
Room_Id Status Inspection_Date
-------------------------------------
1 vacant 5/15/2015
2 occupied 5/21/2015
2 vacant 1/19/2016
1 occupied 12/16/2015
4 vacant 3/25/2016
3 vacant 8/27/2015
1 vacant 4/17/2016
3 vacant 12/12/2015
3 vacant 3/22/2016
4 occupied 2/2/2015
4 vacant 3/24/2015
TABLE_B:
Room_Id Status Inspection_Date
------------------------------------
1 vacant 5/15/2015
2 occupied 5/21/2015
2 vacant 1/19/2016
1 vacant 12/16/2015
1 vacant 4/17/2016
My result should look like this:
Room_Id Status Inspection_Date
---------------------------------
3 vacant 8/27/2015
3 vacant 12/12/2015
3 vacant 3/22/2016
4 occupied 2/2/2015
4 vacant 3/24/2015
4 vacant 3/25/2016
I have tried it this way, it works with the example but is not working with my data .. the logic is not complete:
With cteA As
(
Select *, Row_Number() Over (Partition By Room_ID, Status Order By Inspection_Date Desc) RowNum From Table_A
)
Select * From Table_A Where Room_Id In
(
Select Room_Id
From cteA
Where Room_Id Not In (Select Room_Id From Table_B)
And Status = 'vacant' And RowNum > 1
)
Order By Room_Id, Inspection_Date
Here is the schema:
CREATE TABLE TABLE_A (`Room_Id` int,
`Status` varchar(55),
`Inspection_Date` Date
);
INSERT INTO TABLE_A (Room_Id, Status, Inspection_Date)
VALUES (1, 'vacant', '5/15/2015'),
(2, 'occupied', '5/21/2015'),
(2, 'vacant', '1/19/2016'),
(1, 'occupied', '12/16/2015'),
(4, 'vacant', '3/25/2016'),
(3, 'vacant', '8/27/2015'),
(1, 'vacant', '4/17/2016'),
(3, 'vacant', '12/12/2015'),
(3, 'vacant', '3/22/2016'),
(4, 'occupied', '2/2/2015'),
(4, 'vacant', '3/24/2015');
CREATE TABLE TABLE_B (`Room_Id` int,
`Status` varchar(55),
`Inspection_Date` Date
);
INSERT INTO TABLE_B (Room_Id, Status, Inspection_Date)
VALUES
(1, 'vacant', '5/15/2015'),
(2, 'occupied', '5/21/2015'),
(2, 'vacant', '1/19/2016'),
(1, 'vacant', '12/16/2015'),
(1, 'vacant', '4/17/2016'),;

Answer 1

PLAIN
For each room in TABLE_A select the last date (as lastDate)
for each room in TABLE_A select previous date (as prevLastDate)
Get room_ids from lastDate which has the status 'vacant' (as lastDateVacant)
Get room_ids from prevLastDate which has the status 'vacant' (as prevLastDateVacant)
Filter TABLE_A to have only IDs which are there in lastDateVacant and prevLastDateVacant (inner)
Filter TABLE_A to have only IDs which are not in TABLE_B (left outer + IS NULL)
As the result you have:
WITH lastDate AS (
SELECT room_id AS room,MAX(inspection_date) AS date
FROM "TABLE_A"
GROUP BY room_id
), prevLastDate AS (
SELECT room_id AS room,MAX(inspection_date) AS date
FROM "TABLE_A" a
INNER JOIN lastDate ON a.room_id = lastDate.room and a.inspection_date < lastDate.date
GROUP BY room_id
), lastDateVacant AS (
SELECT room_id AS room FROM "TABLE_A"
WHERE (room_id,inspection_date) IN (
SELECT room, date FROM lastDate
) AND status = 'vacant'
), prevLastDateVacant AS (
SELECT room_id AS room FROM "TABLE_A"
WHERE (room_id,inspection_date) IN (
SELECT room, date FROM prevLastDate
) AND status = 'vacant'
)
SELECT a.* FROM "TABLE_A" a
INNER JOIN lastDateVacant
ON a.room_id = lastDateVacant.room
INNER JOIN prevLastDateVacant
ON a.room_id = prevLastDateVacant.room
LEFT OUTER JOIN "TABLE_B" AS b
ON a.room_id = b.room_id
WHERE b.room_id IS NULL
ORDER BY a.room_id ASC, a.inspection_date DESC
Window Function
Not sure if the syntax for TSQL is the same, but here is the shorter variant:
Ranking with partion by room and or order by date
Check for IDs with rank 1 and 2 having 'vacant' status, grouping by ID and having them occured more than once
WITH room AS (
select room from (
select room_id as room,status,inspection_date as date,
RANK() OVER (PARTITION BY room_id ORDER BY inspection_date DESC) AS RANK
from "TABLE_A"
)
where (rank in ( 1,2) and status = 'vacant')
group by room
having count() > 1
)
SELECT a. FROM "TABLE_A" a
INNER JOIN room
ON a.room_id = room.room
LEFT OUTER JOIN "TABLE_B" AS b
ON a.room_id = b.room_id
WHERE b.room_id IS NULL
ORDER BY a.room_id ASC, a.inspection_date DESC

Answer 2

Your conditions translate almost directly into a query. You can use window functions for the vacant count and not exists for the relationship to table_b:
select a.*
from (select a.*,
sum(case when status = 'vacant' then 1 else 0 end) over (partition by room_id) as num_vacant
from table_a a
where not exists (select 1
from table_b b
where b.room_id = a.room_id
)
) a
where num_vacant >= 2;
EDIT:
If you want the last two to be vacant, you can do find that last record that is non-vacant and then count the ones bigger than that:
select a.*
from (select a.*,
sum(case when a2.max_nonvacant > a.inspection_date then 0 else 1) over (partition by room_id) as num_vacant_last
from table_a a outer apply
(select max(inspection_date) as max_nonvacant
from table_a a2
where a2.room_id = a.room_id and a2.status <> 'vacant'
) a2
where not exists (select 1
from table_b b
where b.room_id = a.room_id
)
) a
where num_vacant_last >= 2;

Answer 3

This worked for me and I have checked again and again.
with Rooms as (
select
Room_Id, Status,
row_number() over (partition by Room_Id order by Inspection_Date desc) as rn
from TABLE_A
), Candidates as (
select Room_Id from Rooms group by Room_Id
having sum(case when rn in (1, 2) and Status = 'vacant' then 1 else null end) = 2
)
select * from TABLE_A
where Room_Id in (select Room_Id from Candidates except select Room_Id from TABLE_B)
order by Room_Id, Inspection_Date desc

Answer 4

I did this test:
extracts all the room_id that considering the last two Status (equal status) in relation to the inspection_date (descending order):
select * from TABLE_A WHERE [Room_Id] IN
(
SELECT [Room_Id] FROM
(SELECT ROW_NUMBER() OVER(PARTITION BY [Room_Id] ORDER BY [Inspection_Date] DESC ) AS id,
[Room_Id],[Status],[Inspection_Date]
FROM TABLE_A
) AA
WHERE AA.ID <=2
--selecting the last two Inspection_Date
and [Status] = 'vacant'
GROUP BY [Room_Id],[Status] HAVING COUNT(*) >1
)
AND
[Room_Id] NOT IN (SELECT Room_Id FROM TABLE_B)
order by Room_Id, Inspection_Date desc