Get Results based on the latest date in a Joined table - sql

Question

I have 2 tables tbl_job & tbl_appointment
I want to get all active jobs starting with job_refrence = '1%' also the latest active appointment.created_when and appointment_type associated with it ordered by the appointment.created_when
A job can have many appointments
If all the appointments associated with the job has deleted_flag = 1
then the resultset should return tbl_job.created-when as the
latest_appointment_date
CREATE TABLE [dbo].[tbl_job]
(
[job_id] UNIQUEIDENTIFIER NOT NULL,
[account_id] INT NOT NULL,
[description] NVARCHAR(1024) NULL,
[deleted_flag] BIT NOT NULL,
[created_when] DATETIME2 (6) NOT NULL,
[job_reference] NVARCHAR(15) NOT NULL
)
CREATE TABLE [dbo].[tbl_appointment]
(
[appointment_id] UNIQUEIDENTIFIER NOT NULL,
[job_id] UNIQUEIDENTIFIER NOT NULL,
[deleted_flag] BIT NOT NULL,
[appointment_type] NVARCHAR(35) NOT NULL,
[created_when] DATETIME2 (6) NOT NULL,
[account_id] INT NULL,
)
insert into dbo.tbl_job (job_id, account_id, [description], deleted_flag, created_when, job_reference) values
('A29A6381-EF0D-47F6-BFC3-051679E343D0', 1, 'descr1', 0, '2020-06-12 00:58:17.7221410', 1 )
,('4D8C1B04-9E00-41FA-BDB8-653C26712144', 1, 'descr2', 0, '2020-06-10 00:58:17.7221410', 12 )
,('F8DC690E-74AB-46F4-90D3-55E032F21C99', 1, 'descr3', 0, '2020-06-26 00:58:17.7221410', 123 )
,('C5D8AA45-FA45-41A4-877D-5B803C1BE61B', 1, 'descr4', 0, '2020-06-27 00:58:17.7221410', 76 )
insert into dbo.tbl_appointment(appointment_id, job_id, deleted_flag, appointment_type, created_when, account_id) Values
('9E24451F-5703-414F-ACF1-9304AFBEA8F1', 'A29A6381-EF0D-47F6-BFC3-051679E343D0', 0, 'job1_cat1', '2020-06-12 00:58:17.7221410', 1)
,('A8121DC1-271E-4BD0-A6AA-D753CF4D310E', 'A29A6381-EF0D-47F6-BFC3-051679E343D0', 0, 'job1_cat2', '2020-06-14 00:58:17.7221410', 1)
,('61ED5B48-DF95-4FC8-AF1D-1418C6DD9088', '4D8C1B04-9E00-41FA-BDB8-653C26712144', 0, 'job2_cat1', '2020-06-15 00:58:17.7221410', 1)
,('0e4fc735-96c3-4cab-8ade-796bae4639d1', 'F8DC690E-74AB-46F4-90D3-55E032F21C99', 1, 'job3_cat1', '2020-06-28 00:58:17.7221410', 1)
Expected ResultSet
job_id job_reference latest_appointment_date appointment_type total_rows
F8DC690E-74AB-46F4-90D3-55E032F21C99 123 2020-06-26 00:58:17.722141 NULL 3
4D8C1B04-9E00-41FA-BDB8-653C26712144 12 2020-06-15 00:58:17.722141 job2_cat1 3
A29A6381-EF0D-47F6-BFC3-051679E343D0 1 2020-06-14 00:58:17.722141 job1_cat2 3
Below query works, but its not an efficient as we have millions of rows in the tables. I would like to replace the OUTER apply with a Left join or some other way to make it more efficient
DECLARE #filtered_jobs TABLE
(
job_domain_id UNIQUEIDENTIFIER
,job_reference NVARCHAR(15)
,job_created_when DATETIME2(6)
,latest_appointment_date DATETIME2(6)
,appointment_type NVARCHAR(35)
);
declare #account_id int = 1
declare #job_reference nvarchar(35) = '1'
declare #offset int = 0
declare #limit int = 10
declare #is_sort_ascending int = 0
INSERT INTO #filtered_jobs (job_domain_id, job_reference, job_created_when, latest_appointment_date,appointment_type)
SELECT
j.job_id
,j.job_reference
,j.created_when
,ap.created_when AS latest_appointment_date
,ap.appointment_type
FROM dbo.tbl_job j
OUTER APPLY (
SELECT TOP (1) ap.appointment_type,ap.created_when,ap.deleted_flag
FROM dbo.tbl_appointment ap
WHERE ap.job_id = j.job_id AND ap.deleted_flag = 0
ORDER BY ap.created_when desc
) ap
WHERE j.account_id = #account_id
AND j.job_reference LIKE (#job_reference + '%')
AND j.deleted_flag = 0
SELECT
fj.job_domain_id
,fj.job_reference
,ISNULL(fj.latest_appointment_date,fj.job_created_when) AS latest_appointment_date
,fj.appointment_type
FROM #filtered_jobs fj
ORDER BY
CASE WHEN #is_sort_ascending = 0 THEN ISNULL(fj.latest_appointment_date,fj.job_created_when) END DESC,
CASE WHEN #is_sort_ascending = 1 THEN ISNULL(fj.latest_appointment_date,fj.job_created_when) END ASC
OFFSET #offset ROWS FETCH NEXT #limit ROWS ONLY;
SELECT COUNT(1) AS total_records
FROM #filtered_jobs;

Answer 1

You could use a ranking function but you need to test whether it is faster:
From the query you posted, replace the insert into #filtered_jobs with these 2:
INSERT INTO #filtered_jobs (job_domain_id, job_reference, job_created_when)
select j.job_id
,j.job_reference
,j.created_when
FROM dbo.tbl_job j
WHERE j.account_id = #account_id
AND j.job_reference LIKE (#job_reference + '%')
AND j.deleted_flag = 0
update f
set latest_appointment_date=x.latest_appointment_date,
appointment_type=x.appointment_type
from #filtered_jobs f
inner join (
select f.job_domain_id
,ap.created_when AS latest_appointment_date
,ap.appointment_type as appointment_type
, rank() over (partition by ap.job_id order by ap.created_when desc) rnk
from #filtered_jobs f
inner join dbo.tbl_appointment ap on ap.job_id = f.job_domain_id
where ap.deleted_flag = 0) x on f.job_domain_id=x.job_domain_id
where x.rnk=1
Make sure you have a index on dbo.tbl_appointment(column job_id, ap.deleted_flag), preferably including (created_when, appointment_type) if this query is ran alot.