set serveroutput on
declare
s_sql varchar2(2000);
s_rez varchar2(32767);
begin
s_sql := 'select LONG_COLUMN from SOME_TABLE where ID_COLUMN = 123' ;
execute immediate s_sql into s_rez;
-- print it on the screen or convert/transform/search...
dbms_output.put_line ( s_rez ) ;
end;