selecting dates based on a condition

[Adnan_Razaq]

data have;
 input Acc  code $ effective_date possession_date;
  datalines;
    1 PO 14JUN2016 29NOV2011

    1 LA  16FEB2012 29NOV2011

    1 LB 14JUN2016 .

    2 LA 29MAR2007 27MAY2010

    2 LB 29MAR2007 28MAY2010       
;
run;

From this dataset what I need is if the if the codes are PO or LB and effective date is greater than possesison date the possession_date1 is effective date (of the latest PO or LB codes) else possession_date1 is equal to possession date.

[Tom]

Can you add what you want the result to look like?

[PeterClemmensen]

What does your desired output look like? 🙂 What happens when there is a missing value?

[Adnan_Razaq]

The output which I require should look like

Want

Acc Possession_date1

1     29NOV2011

2     29MAR20017

The dataset contains either or both of the effective_date and possession_date. If either are missing the popukated date is to be used.

Thanks

Adnan