I'm not sure if you still need this, but here is an example of a solution I found on the Internet (and it's on SQL level so you don't need to worry about complicated XML codes):
SELECT '="' || q.item_code || '"' excel_display_item_code
FROM (SELECT '00005689' item_code FROM DUAL
UNION
SELECT '00000012' item_code FROM DUAL
UNION
SELECT '01345677' item_code FROM DUAL) q;