SAS Proc SQL Inner join

proc_sql_inner_join.sas

proc sql;
  create table work.dsOut as
  /* a.* means all records from work.dsIn
    b.effdate means select effdate from misc.sdc
  /
  select a.*, b.effdate 
  from work.dsIn a 
  /* perform a left join */
  left join misc.sdc b 
  /* require that gvkey is the same */
  on a.gvkey = b.gvkey 
  /* and that the effdate is in the 365 day period before datadate */
  and a.datadate - 365 <= b.effdate <= a.datadate;
quit;