How to remove duplicate SQL rows based off 1 column by comparing 2 different date columns? - sql

Question

I have a query that joins multiple tables/views and displays rows that are identified by a column named VIN. I want to only show the VIN one time based off of the most recent date from 2 different date fields (OPEN DATE & INVOICE DATE) IF both dates have a Value.
If Invoice Date is Null, show the row that has the most recent Open Date for that VIN. For example, if I have 3 rows for VIN='XY123456' and
Row 1 shows Open Date 3/1/2019 and Invoice Date NULL, and
Row 2 shows Open Date 3/15/2019 and Invoice Date 3/28/2019, and
Row 3 shows Open Date 4/1/2019 and Invoice Date 4/5/2019,
I want to return Row 1 since the Invoice Date is NULL and it is the most recent Open Date for that VIN.
Had there been an Invoice Date for Row 1, we would return the row with the most recent date from either date column.
I have tried ELSE clause and COALASCE without success. I also tried doing a subquery to use MAXDATE.
SELECT RO.[RepairOrderID]
,RO.[CompanyName]
,CUS.CustomerKey
,UN.UnitNumber AS 'UNIT #'
,ISNULL(UC.[Tag #],'') AS 'S #'
,UN.Year
,UN.Make
,UN.Model
,UN.VIN
,ROS.[RepairOrderStatus] AS 'STATUS'
,RO.RepairOrderNumber AS 'RO #'
,CONVERT(VARCHAR(2),DATEPART(month, RO.[OpenDate]))
+ '/'+ CONVERT(VARCHAR(2),DATEPART(DAY, RO.[OpenDate]))
+ '/' + CONVERT(VARCHAR(4),DATEPART(YEAR, RO.[OpenDate]))
'OPEN DATE'
,CONVERT(VARCHAR(2),DATEPART(month, ROI.InvoiceDate))
+ '/'+ CONVERT(VARCHAR(2),DATEPART(DAY, ROI.InvoiceDate))
+ '/' + CONVERT(VARCHAR(4),DATEPART(YEAR, ROI.InvoiceDate))
'INVOICE DATE'
FROM [ProfitMaster].[dbo].[RepairOrder] RO with (nolock)
INNER JOIN [ProfitMaster].[dbo].[vwAC_SSR_Customer] CUS with (nolock)
ON CUS.CustomerID = RO.CustomerID
INNER JOIN [ProfitMaster].[dbo].[RepairOrderStatus] ROS with (nolock)
ON ROS.RepairOrderStatusID = RO.RepairOrderStatusID
LEFT OUTER JOIN [ProfitMaster].[dbo].[RepairOrderInvoice] ROI with (nolock)
ON ROI.RepairOrderID = RO.RepairOrderID
LEFT OUTER JOIN [ProfitMaster].[dbo].[vwSR_SSR_Unit] UN with (nolock)
ON UN.UnitInventoryID = RO.UnitInventoryID
LEFT OUTER JOIN [ProfitMaster].[dbo].[vwSR_SSR_UnitCharacteristics] UC with (nolock)
ON UC.UnitInventoryID = Ro.UnitInventoryID
WHERE ((ROS.RepairOrderStatus IN ('OPEN')
OR (ROS.RepairOrderStatus = 'QUOTE' AND RO.OpenDate >= (getDate()- 90)))
OR (ROS.RepairOrderStatus = 'INVOICED' AND ROI.InvoiceDate > '2019-01-01 00:00:00.000'))
AND (CUS.InternalAccount = '0' AND CUS.InternalLRCustomer = '0')
Results Sample: