Few days ago I had to develop dynamic query json export module. As a sandbox I prepared PLSQL block: DECLARE c sys_refcursor; l_sql varchar2(4000) := 'select null as "col1", 100 as "col2" from dual union all select 200 as "col1", null as "col2" from dual'; l_file clob; BEGIN open c for l_sql; apex_json.initialize_clob_output; apex_json.open_object; apex_json.write('rowset', c); apex_json.close_object; l_file := apex_json.get_clob_output; apex_json.free_output; DBMS_OUTPUT.PUT_line(l_file); END; { "rowset": [{ "col2": 100 }, { "col1": 200 } ] } As you can see above PLSQL code doesn't return null value pairs : ( apex_json.write(p_name IN VARCHAR2, p_cursor IN OUT NOCOPY sys_refcursor) procedure Signature 14 doesn't support null. How to fix it... ? APEX API provides apex_js