How to get MAX values in JOINs in SQL Server 2014? - sql

Question

I have 4 tables that I need to join to pull data from:
| Account Table: A | Plate Table: P | TollTransaction : T | FinTrans Table: F |
=================================================================================
| AccountId | AccountId | AccountId | AcctId |
| AccountNumber | LicPlateNo | LicPlateNo | FinTransTypeCode |
| CurrentBalance | EndDate | EntryTransDt | BusinessDay |
| ActualTagDeposit | | | |
=================================================================================
The relationships:
A.AccountId = P.AccountId = F.AcctId != T.AccountId <--(NOT EQUAL)
P.LicPlateNo = T.LicPlateNo
I want to show:
A.AccountNumber
A.CurrentBalance
Max(BusinessDay) -->(Last Payment Date)
Max(EntryTransDt) -->(Last Transaction Date)
ActualTagDeposit
WHERE P.EndDate IS NULL
AND A.CurrentBalance > 0
AND F.FinTransTypeCode = 'pymt'
AND Max(EntryTransDt) <= '2017-07-28'
AND A.ActualTagDeposit >= 10
My attempt at the code so far:
SELECT A.AccountNumber
,A.CurrentBalance
,MAX(F.Last_Pymt_date) AS Last_Pymnt_Date
,MAX(T.Last_Transaction) AS LastTransaction
,A.ActualTagDeposit
FROM
( SELECT AccountId
,LicPlateNo
,MAX(EntryTransDt) AS Last_Transaction
FROM TollTransaction
GROUP BY AccountId, LicPlateNo
) T
INNER JOIN Plate P ON T.LicPlateNo = P.LicPlateNo
INNER JOIN Account A ON P.AccountId = A.AccountId
LEFT JOIN
( SELECT AcctId
,FinTransTypeCode
,MAX(BusinessDay) AS Last_Pymt_Date
FROM FinTransMaster
GROUP BY AcctID, FinTransTypeCode
) F ON A.AccountId = F.AcctId
WHERE P.EndDate is null
AND A.CurrentBalance > 0
AND F.FinTransTypeCode = 'pymt'
AND Last_Transaction <= '2017-07-28'
AND A.ActualTagDeposit >= 10
GROUP BY AccountNumber, CurrentBalance, Last_Pymt_date, Last_Transaction, A.ActualTagDeposit
ORDER BY AccountNumber
But I get duplicates with this code. Obviously, the MAX part in my code is not working somehow?
A sample of the results I get:
AccountNumber CurrentBalance Last_Pymnt_Date LastTransaction ActualTagDeposit
21233815 12.34 2016-12-12 2016-08-15 10.00
21233815 12.34 2016-12-12 2017-03-11 10.00
21234567 123.12 2017-06-20 2016-12-25 10.00
21234568 1.23 2017-06-05 2012-07-12 10.00
21234568 1.23 2017-06-05 2012-07-21 10.00

Answer 1

This is happening because one account can have multiple license plates. If you added P.LicPlateNo to your current select, you would see something like this:
AccountNumber CurrentBalance Last_Pymnt_Date LastTransaction ActualTagDeposit LicPlateNo
21233815 12.34 2016-12-12 2016-08-15 10.00 A123
21233815 12.34 2016-12-12 2017-03-11 10.00 B456
I would like to say just remove Plates all together, but it seems like you have to use it as the link to table T, so the next best move is to do a MAX() in your outer query (as you are doing). The problem is that you also have the maxed columns in your outer GROUP BY, which prevents them from being aggregated in your MAX()
Changing your outer group by will solve the problem:
GROUP BY AccountNumber, CurrentBalance, A.ActualTagDeposit