Oracle: convert LONG to VARCHAR2

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;