SUBSTR Using before spae

   declare
  a varchar2(100);
  v_output varchar2(100);
  begin
  a:='HCL HR';
   SELECT substr('HCL HR',1,instr('HCL HR',' ')-1) into v_output from dual;
  dbms_output.put_line(v_output);
  end;

   OUTPUT
==========
HCL