1. Saving Data Steps with the Proc SQL Self-join Yan Wang Population Health Research Unit (PHRU) Dalhousie University

2. The Task ObsID indexdate exdate 11 28MAR2001. 21 28APR2001 28APR2001 31 29JAN2004. 42 28JUN1997. 52 02JAN1998 02JAN1998 62 08JAN1998 08JAN1998 7 2 15FEB1998 15FEB1998 8 2 23FEB1998. 9 2 11JUN1999. One data set with 2 dates: indexdate and exdate For each individual, subsetting records whose indexdate in the 120 days before or 90 days after exdate

3. proc sql; select a.*, (-90<= b.exdate-a.indexdate <=120) as diff from temp as a, temp as b where a.ID=b.ID; quit; Obs ID indexdate exdate diff 1 1 28MAR2001. 0 2 1 28APR2001 28APR2001 0 3 1 29JAN2004. 0 4 1 28MAR2001. 1 5 1 28APR2001 28APR2001 1 6 1 29JAN2004. 0 7 1 28MAR2001. 0 8 1 28APR2001 28APR2001 0 9 1 29JAN2004. 0 Obs ID indexdate exdate 1 1 28MAR2001. 2 1 28APR2001 28APR2001 3 1 29JAN2004. Obs ID indexdate exdate 1 1 28MAR2001. 2 1 28APR2001 28APR2001 3 1 29JAN2004. Comparing

4. Obs ID indexdate exdate diff 1 1 28MAR2001. 0 21 2 11JUN1999. 0 2 1 28APR2001 28APR2001 0 22 2 28JUN1997. 0 3 1 29JAN2004. 0 23 2 02JAN1998 02JAN1998 1 4 1 28MAR2001. 1 24 2 08JAN1998 08JAN1998 1 5 1 28APR2001 28APR2001 1 25 2 15FEB1998 15FEB1998 1 6 1 29JAN2004. 0 26 2 23FEB1998. 1 7 1 28MAR2001. 0 27 2 11JUN1999. 0 8 1 28APR2001 28APR2001 0 28 2 28JUN1997. 0 9 1 29JAN2004. 0 29 2 02JAN1998 02JAN1998 1 10 2 28JUN1997. 0 30 2 08JAN1998 08JAN1998 1 11 2 02JAN1998 02JAN1998 0 31 2 15FEB1998 15FEB1998 1 12 2 08JAN1998 08JAN1998 0 32 2 23FEB1998. 1 13 2 15FEB1998 15FEB1998 0 33 2 11JUN1999. 0 14 2 23FEB1998. 0 34 2 28JUN1997. 0 15 2 11JUN1999. 0 35 2 02JAN1998 02JAN1998 0 16 2 28JUN1997. 0 36 2 08JAN1998 08JAN1998 0 17 2 02JAN1998 02JAN1998 1 37 2 15FEB1998 15FEB1998 0 18 2 08JAN1998 08JAN1998 1 38 2 23FEB1998. 0 19 2 15FEB1998 15FEB1998 1 39 2 11JUN1999. 0 20 2 23FEB1998. 1 40 2 28JUN1997. 0 41 2 02JAN1998 02JAN1998 0 42 2 08JAN1998 08JAN1998 0 43 2 15FEB1998 15FEB1998 0 44 2 23FEB1998. 0 45 2 11JUN1999. 0

5. proc sql; select distinct a.*, sum(-90 0 as index from temp as a, temp as b where a.ID=b.ID group by a.ID, a.indexdate; quit; Obs ID indexdate exdate index 1 1 28MAR2001. 1 2 1 28APR2001 28APR2001 1 3 1 29JAN2004. 0 4 2 28JUN1997. 0 5 2 02JAN1998 02JAN1998 1 6 2 08JAN1998 08JAN1998 1 7 2 15FEB1998 15FEB1998 1 8 2 23FEB1998. 1 9 2 11JUN1999. 0 Identifying

6. proc sql; create table tp as select distinct a.*, sum(-90 0 as index from temp as a, temp as b where a.ID=b.ID group by a.ID, a.indexdate having index = 1; quit; Subsetting Obs ID indexdate exdate index 1 1 28MAR2001. 1 2 1 28APR2001 28APR2001 1 3 2 02JAN1998 02JAN1998 1 4 2 08JAN1998 08JAN1998 1 5 2 15FEB1998 15FEB1998 1 6 2 23FEB1998. 1

7. Reference Subsetting SAS ® Data Set by Using PROC SQL Self-join with Compound Key Zizhong Fan, Westat, Rockville, MD http://www2.sas.com/proceedings/sugi29/065-29.pdf