You can use regular expressions within SQL. This can be quite powerful in selecting data that matches certain conditions. The following example shows a simple regular expression which selects only quarterly periods from a table containing years, quarters & months.

data test ;
 
  length period $ 7 ;
 
  input period ;
 
cards ;
 
2005
 
2005Q1
 
2005JAN
 
;;
 
run ;
 
proc sql;
 
  create table qtrs as
 
    select *
 
      from test
 
        where prxmatch("/\d\d\d\d[qQ][1-4]/",period) ;
 
quit;
 
proc print data=qtrs ;
 
run ;