keep only variables that exists

*list of variables needed;
%let keeplist= "STUDYID","USUBJID","MHSPID","MHSEQ","MHTERM","MHLLT","MHLLTCD","MHDECOD","MHPTCD","MHHLT","MHHLTCD","MHHLGT","MHHLGTCD","MHBODSYS",
"MHBDSYCD","MHSOC","MHSOCCD","MHCAT","MHSCAT","MHENRTPT","MHENTPT ","MHSTRTPT","MHSTTPT ","MHPRESP","MHOCCUR","DIAGAGE","DIAGMETH",
"DNASPMUT","DNASPEXN","DNASPPLY","MHAGEST","MHAGEEN";

*bring in sdtm;
%qc_combinesdtm(dsnam=mh);

data admh1;
 set mh(in=a);
  by usubjid;
  if a;

  adadiage= input(diagage, best.);
  adameth= diagmeth;


run;

*variables that are populated;
proc sql noprint;
  select name
  into: newkeeplist separated by ", "
  from sashelp.vcolumn
  where libname= "WORK" and memname="ADMH1" and name in (&keeplist);
quit;