T-SQL join query using distinct values from second table - sql-server

Question

I know this question might sound like a duplicate, but I've been through every question I could find; though it's still possible it might be a duplicate of a question I might have missed.
I have what at surface value appears to be a trivial requirement but no matter how I script it out there's always some caveat that's just not working. I've tried GROUP, DISTINCT, JOIN, aggregate functions, etc.
Scenario:
PRIMARYTABLE contains a set of campaigns and SECONDARYTABLE contains the dates on which campaigns were run. There can be multiple runs per campaign and I've included a SUBKEY for each run.
Requirement:
I need to be able to get the most recently run campaigns into a list so the user can more easily select from the campaigns that get run the most frequent.
PRIMARYTABLE
KEYCOLUMN INFOCOLUMN
100000 Test 1
100001 Test Campaign
100002 Test Image 2
100003 Test Img
100004 Image Test
100005 Test
100006 Test Image 3
100007 Test Image 4
100008 Test Image 5
100009 Image Comparison Test 2
100010 Testing
100011 Test Fields
100012 Test 5
100013 test
SECONDARYTABLE
KEYCOLUMN SUBKEY DATECOLUMN
100000 100000 2017-06-02 04:09:57.593
100001 100001 2017-06-19 12:09:54.093
100001 100002 2017-06-27 10:51:14.140
100004 100003 2017-06-27 12:33:47.747
100006 100004 2017-06-28 10:29:53.387
100007 100005 2017-06-28 10:36:23.710
100008 100006 2017-06-29 22:31:03.790
100009 100007 2017-06-29 23:07:52.870
100009 100010 2017-10-04 16:05:40.583
100009 100011 2017-10-04 16:09:55.470
100011 100008 2017-09-08 14:02:28.017
100012 100009 2017-09-11 16:17:23.870
100013 100012 2017-11-07 16:55:55.403
100013 100013 2017-11-08 15:37:16.430
Below is somewhat of an idea of more or less what I'm after.
SELECT DISTINCT( a.[INFOCOLUMN] )
FROM [PRIMARYTABLE] a
INNER JOIN [SECONDARYTABLE] b ON ( a.[KEYCOLUMN] = b.[KEYCOLUMN] )
ORDER BY a.[DATECOLUMN]
Here's hoping for a Homer Simpson "Doh!" moment once I see how it's supposed to be done.
Much appreciated.

Answer 1

the most recently run campaigns >> use row_number() over(.. order by ... DESC)
that get run the most frequent >> use count(*) over(partition by ..)
Using window functions row_number() over() and count() over() enables selection by row of data that is "most recent" and ordering by "most frequent". Note that the DESCending order of dates brings about "recent" = 1.
select
p.*, s.*
from PRIMARYTABLE p
inner join (
select KEYCOLUMN, SUBKEY, DATECOLUMN
, row_number() over(partition by KEYCOLUMN order by DATECOLUMN DESC) recent
, count(*) over(partition by KEYCOLUMN) frequency
from SECONDARYTABLE
) s on p.KEYCOLUMN = s.KEYCOLUMN and s.recent = 1
order by s.frequency DESC, p.INFOCOLUMN

Answer 2

You can try this:
DECLARE #PRIMARYTABLE TABLE
(
[KEYCOLUMN] INT
,[INFOCOLUMN] VARCHAR(24)
);
DECLARE #SECONDARYTABLE TABLE
(
[KEYCOLUMN] INT
,[SUBKEY] INT
,[DATECOLUMN] DATETIME2
);
INSERT INTO #PRIMARYTABLE ([KEYCOLUMN], [INFOCOLUMN])
VALUES (100000, 'Test 1')
,(100001, 'Test Campaign')
,(100002, 'Test Image 2')
,(100003, 'Test Img')
,(100004, 'Image Test')
,(100005, 'Test')
,(100006, 'Test Image 3')
,(100007, 'Test Image 4')
,(100008, 'Test Image 5')
,(100009, 'Image Comparison Test 2')
,(100010, 'Testing')
,(100011, 'Test Fields')
,(100012, 'Test 5')
,(100013, 'test');
INSERT INTO #SECONDARYTABLE ([KEYCOLUMN], [SUBKEY], [DATECOLUMN])
VALUES (100000, 100000, '2017-06-02 04:09:57.593')
,(100001, 100001, '2017-06-19 12:09:54.093')
,(100001, 100002, '2017-06-27 10:51:14.140')
,(100004, 100003, '2017-06-27 12:33:47.747')
,(100006, 100004, '2017-06-28 10:29:53.387')
,(100007, 100005, '2017-06-28 10:36:23.710')
,(100008, 100006, '2017-06-29 22:31:03.790')
,(100009, 100007, '2017-06-29 23:07:52.870')
,(100009, 100010, '2017-10-04 16:05:40.583')
,(100009, 100011, '2017-10-04 16:09:55.470')
,(100011, 100008, '2017-09-08 14:02:28.017')
,(100012, 100009, '2017-09-11 16:17:23.870')
,(100013, 100012, '2017-11-07 16:55:55.403')
,(100013, 100013, '2017-11-08 15:37:16.430');
SELECT a.[INFOCOLUMN]
,b.[DATECOLUMN]
FROM #PRIMARYTABLE A
CROSS APPLY
(
SELECT TOP 1 [DATECOLUMN]
FROM #SECONDARYTABLE B
WHERE A.[KEYCOLUMN] = B.[KEYCOLUMN]
ORDER BY [DATECOLUMN] DESC
) b;
It will give you the last execution of each campaign. You can filter then by date or ORDER BY and get TOP N from the final query.
Or you can use ROW_NUMBER:
WITH DataSource AS
(
SELECT A.[INFOCOLUMN]
,B.[DATECOLUMN]
,ROW_NUMBER() OVER (PARTITION BY A.[KEYCOLUMN] ORDER BY B.[KEYCOLUMN]) AS [RowID]
FROM #PRIMARYTABLE A
INNER JOIN #SECONDARYTABLE B
ON A.[KEYCOLUMN] = B.[KEYCOLUMN]
)
SELECT [INFOCOLUMN]
,[DATECOLUMN]
FROM DataSource
WHERE [RowID] = 1;

Answer 3

try this, it will return the list of campaigns in most frequent order of use. Note campaigns never run wont appear in your list. in this case you will to do a left join
SELECT a.[INFOCOLUMN]
FROM [PRIMARYTABLE] a
/* left */ JOIN [SECONDARYTABLE] b ON a.[KEYCOLUMN] = b.[KEYCOLUMN]
group BY a.[infocolumn]
order by max(datecolumn) desc
here is a stub i did to test it
select 10000 id,'Campain A' cname into #a1 union all
select 10002,'Campain B' union all
select 10004,'Campain C' union all
select 10009,'Campain E'
select 10000 id,'20170101' thedate into #a2 union all
select 10000,'20170102' union all
select 10009,'20170103' union all
select 10002,'20170104' union all
select 10004,'20170105' union all
select 10000,'20170201' union all
select 10000,'20170302' union all
select 10009,'20170403' union all
select 10002,'20170104' union all
select 10004,'20170205' union all
select 10000,'20170101' union all
select 10004,'20170302' union all
select 10000,'20170103' union all
select 10002,'20170404' union all
select 10002,'20170105'
select #a1.cname
from #a1 join #a2 on #a1.id = #a2.id
group by #a1.cname
order by max(thedate) desc