What is the best way to do this? The actual datasets are millions of obs..  one small (A) against one huge (~10m) B) but i need A to loop through B and find matches based on date conditions. once each single observation on A has looped through B, i need it to do the same for the nexst observation in A and so  on A month begin   end Jan19   1/1/2019  1/31/2019 Feb19   2/1/2019  2/28/2019 B custid recur_start recur_end recur_amt 1 10/15/2014 2/16/2019 150 2 2/18/2018 1/31/2019 150 3 12/15/2012 3/31/2021 100  result dataset needed: month custid recur_start recur_end recur_amt Jan19 1 10/15/2014 2/16/2019 150 Jan19 2 2/18/2018 1/31/2019 150 Jan19 3 12/15/2012 3/31/2021 100 Feb19 1 10/15/2014 2/16/2019 150  Feb19 3 12/15/2012 3/31/2021 100 ... View more

I am stumped on how to get something to work. I need to use point= do loop to accompish the following: Dataset1: Promise acctnum  promisedate promiseamt bwindow  ewindow 100  3/15/2015 100  3/15/2015 3/28/2015 100  3/21/2015 150  3/21/2015 4/1/2015 Dataset2: Payments acctnum  paydate  payamt 100  3/21/2015 100 100  3/25/2015 150 I need the to evaluate each promise record by acctnum for a matching payment record (with same acctnum) within the date range (pdate and ewindow) and mark the promise found, but I also need to mark the payment as used so it is not used again to evaluate the next promise record for that account number.  What i have is below, but the issue is the first payment is used twice becuase it is the first payment in the specified range for both promises.  Anyone have any ideas? data promisekey; set promise; by acctnum ewindow; retain firstpr; if first.acctnum then firstpr=_n_; if last.acctnum then do;   lastpr=_n_;   output; end; run; data paymentkey; set payments; by acctnum paydate; retain firstpy; if first.acctnum then firstpy=_n_; if last.acctnum then do;   lastpy=_n_;   output; end; run; data keys (keep=acctnum firstpr lastpr firstpy lastpy); merge promisekey (in=a) paymentkey; by acctnum; if a; run; data final; set keys; do i=firstpr to lastpr; set promise point=i; format recdate yymmddn8.; format bwindow yymmddn8.; format ewindow yymmddn8.; format paydate yymmddn8.; format paid comma21.2; recdate=.; paid=.; if firstpy ne . then do j=firstpy to lastpy until (found); found=0;    set payments point=j ;   if paydate ge pdate and paydate le ewindow  then do;    recdate=paydate;    paid=amount;    found=1;      end;   end; output; end; run; This is what outputs (trimmed down with only some variables): acctnum  promisedate promiseamt ewindow  found  paydate  payamt 100  3/15/2015 100  3/28/15  1  3/21/15  100 100  3/21/2015 150  4/1/2015 1  3/21/15  100 This is what i need it to output: acctnum  promisedate promiseamt ewindow  found  paydate  payamt 100  3/15/2015 100  3/28/15  1  3/21/15  100 100  3/21/2015 150  4/1/2015 1  3/25/15  150 Sorry for the long winded request..  but wasn't sure how to explain and still not sure if I made it clear enough. ... View more