Select latest and 2nd latest date rows per user - sql

Question

I have the following query to select rows where the LAST_UPDATE_DATE field is getting records that have a date value greater than or equal to the last 7 days, which works great.
SELECT 'NEW ROW' AS 'ROW_TYPE', A.EMPLID, B.FIRST_NAME, B.LAST_NAME,
A.BANK_CD, A.ACCOUNT_NUM, ACCOUNT_TYPE, PRIORITY, A.LAST_UPDATE_DATE
FROM PS_DIRECT_DEPOSIT D
INNER JOIN PS_DIR_DEP_DISTRIB A ON A.EMPLID = D.EMPLID AND A.EFFDT = D.EFFDT
INNER JOIN PS_EMPLOYEES B ON B.EMPLID = A.EMPLID
WHERE
B.EMPL_STATUS NOT IN ('T','R','D')
AND ((A.DEPOSIT_TYPE = 'P' AND A.AMOUNT_PCT = 100)
OR A.PRIORITY = 999
OR A.DEPOSIT_TYPE = 'B')
AND A.EFFDT = (SELECT MAX(A1.EFFDT)
FROM PS_DIR_DEP_DISTRIB A1
WHERE A1.EMPLID = A.EMPLID
AND A1.EFFDT <= GETDATE())
AND D.EFF_STATUS = 'A'
AND D.EFFDT = (SELECT MAX(D1.EFFDT)
FROM PS_DIRECT_DEPOSIT D1
WHERE D1.EMPLID = D.EMPLID
AND D1.EFFDT <= GETDATE())
AND A.LAST_UPDATE_DATE >= GETDATE() - 7
What I would like to add onto this is to also add the previous (2nd MAX) row per EMPLID, so that I can output the 'old' row (that was prior to the last update the latest row meeting above criteria), along with the new row that I already am outputting in the query.
ROW_TYPE EMPLID FIRST_NAME LAST_NAME BANK_CD ACCOUNT_NUM ACCOUNT_TYPE PRIORITY LAST_UPDATE_DATE
NEW ROW 12345 JOHN SMITH 123548999 45234879 C 999 2019-03-06 00:00:00.000
OLD ROW 12345 JOHN SMITH 214080046 92178616 C 999 2018-10-24 00:00:00.000
NEW ROW 56399 CHARLES MASTER 785816167 84314314 C 999 2019-03-07 00:00:00.000
OLD ROW 56399 CHARLES MASTER 345761227 547352 C 999 2017-05-16 00:00:00.000
So the EMPLID would be ordered by NEW ROW, followed by OLD ROW as shown above. In this example the 'NEW ROW' is getting the record that is within the past 7 days, as indicated by the LAST_UPDATE_DATE.
I would like to get feedback on how to modify the query so I can also get the 'old' row (which is the max row that is less than the 'NEW' row retrieved above).

Answer 1

It was a slow day for crime in Gotham, so I gave this a whirl. Might work.
This is unlikely to work right out of the box, though, but it should get you started.
Your LAST_UPDATE_DATE column is on the table PS_DIR_DEP_DISTRIB, so we'll start there. First, you want to identify all of the records that were updated in the last 7 days because those are the only ones you're interested in. Throughout this, I'm assuming, and I'm probably wrong, that the natural key for the table consists of EMPLID, BANK_CD, and ACCOUNT_NUM. You'll want to sub in the actual natural key for those columns in a few places. That said, the date limiter looks something like this:
SELECT
EMPLID
,BANK_CD
,ACCOUNT_NUM
FROM
PS_DIR_DEP_DISTRIB AS limit
WHERE
limit.LAST_UPDATE_DATE >= DATEADD(DAY, -7, CAST(GETDATE() AS DATE))
AND
limit.LAST_UPDATE_DATE <= CAST(GETDATE() AS DATE)
Now we'll use that as a correlated sub-query in a WHERE EXISTS clause that we'll correlate back to the base table to limit ourselves to records with natural key values that were updated in the last week. I altered the SELECT list to just SELECT 1, which is typical verbiage for a correlated sub, since it stops looking for a match when it finds one (1), and doesn't actually return any values at all.
Additionally, since we're filtering this record set anyway, I moved all the other WHERE clause filters for this table into this (soon to be) sub-query.
Finally, in the SELECT portion, I added a DENSE_RANK to force order the records. We' use the DENSE_RANK value later to filter off only the first (N) records of interest.
So that leaves us with this:
SELECT
EMPLID
,BANK_CD
,ACCOUNT_NUM
--,ACCOUNT_TYPE --Might belong here. Can't tell without table alias in original SELECT
,PRIORITY
,EFFDT
,LAST_UPDATE_DATE
,DEPOSIT_TYPE
,AMOUNT_PCT
,DENSE_RANK() OVER (PARTITION BY --Add actual natural key columns here...
EMPLID
ORDER BY
LAST_UPDATE_DATE DESC
) AS RowNum
FROM
PS_DIR_DEP_DISTRIB AS sdist
WHERE
EXISTS
(
-- Get the set of records that were last updated in the last 7 days.
-- Correlate to the outer query so it only returns records related to this subset.
-- This uses a correlated subquery. A JOIN will work, too. Try both, pick the faster one.
-- Something like this, using the actual natural key columns in the WHERE
SELECT
1
FROM
PS_DIR_DEP_DISTRIB AS limit
WHERE
--The first two define the date range.
limit.LAST_UPDATE_DATE >= DATEADD(DAY, -7, CAST(GETDATE() AS DATE))
AND limit.LAST_UPDATE_DATE <= CAST(GETDATE() AS DATE)
AND
--And these are the correlations to the outer query.
limit.EMPLID = sdist.EMPLID
AND limit.BANK_CD = sdist.BANK_CD
AND limit.ACCOUNT_NUM = sdist.ACCOUNT_NUM
)
AND
(
dist.DEPOSIT_TYPE = 'P'
AND dist.AMOUNT_PCT = 100
)
OR dist.PRIORITY = 999
OR dist.DEPOSIT_TYPE = 'B'
Replace the original INNER JOIN to PS_DIR_DEP_DISTRIB with that query. In the SELECT list, the first hard-coded value is now dependent on the RowNum value, so that's a CASE expression now. In the WHERE clause, the dates are all driven by the subquery, so they're gone, several were folded into the subquery, and we're adding WHERE dist.RowNum <= 2 to bring back the top 2 records.
(I also replaced all the table aliases so I could keep track of what I was looking at.)
SELECT
CASE dist.RowNum
WHEN 1 THEN 'NEW ROW'
ELSE 'OLD ROW'
END AS ROW_TYPE
,dist.EMPLID
,emp.FIRST_NAME
,emp.LAST_NAME
,dist.BANK_CD
,dist.ACCOUNT_NUM
,ACCOUNT_TYPE
,dist.PRIORITY
,dist.LAST_UPDATE_DATE
FROM
PS_DIRECT_DEPOSIT AS dd
INNER JOIN
(
SELECT
EMPLID
,BANK_CD
,ACCOUNT_NUM
--,ACCOUNT_TYPE --Might belong here. Can't tell without table alias in original SELECT
,PRIORITY
,EFFDT
,LAST_UPDATE_DATE
,DEPOSIT_TYPE
,AMOUNT_PCT
,DENSE_RANK() OVER (PARTITION BY --Add actual natural key columns here...
EMPLID
ORDER BY
LAST_UPDATE_DATE DESC
) AS RowNum
FROM
PS_DIR_DEP_DISTRIB AS sdist
WHERE
EXISTS
(
-- Get the set of records that were last updated in the last 7 days.
-- Correlate to the outer query so it only returns records related to this subset.
-- This uses a correlated subquery. A JOIN will work, too. Try both, pick the faster one.
-- Something like this, using the actual natural key columns in the WHERE
SELECT
1
FROM
PS_DIR_DEP_DISTRIB AS limit
WHERE
--The first two define the date range.
limit.LAST_UPDATE_DATE >= DATEADD(DAY, -7, CAST(GETDATE() AS DATE))
AND limit.LAST_UPDATE_DATE <= CAST(GETDATE() AS DATE)
AND
--And these are the correlations to the outer query.
limit.EMPLID = sdist.EMPLID
AND limit.BANK_CD = sdist.BANK_CD
AND limit.ACCOUNT_NUM = sdist.ACCOUNT_NUM
)
AND
(
dist.DEPOSIT_TYPE = 'P'
AND dist.AMOUNT_PCT = 100
)
OR dist.PRIORITY = 999
OR dist.DEPOSIT_TYPE = 'B'
) AS dist
ON
dist.EMPLID = dd.EMPLID
AND dist.EFFDT = dd.EFFDT
INNER JOIN
PS_EMPLOYEES AS emp
ON
emp.EMPLID = dist.EMPLID
WHERE
dist.RowNum <= 2
AND
emp.EMPL_STATUS NOT IN ('T', 'R', 'D')
AND
dd.EFF_STATUS = 'A';