[thelist] Calculat on calculation in SQL?

Does anyone know if it is possible to do this?

select cycleNumber,
cycleDate,
cycleDateDue,
DATE_ADD(cycleDateDue, INTERVAL 5 DAY) AS ReminderLetterDate,
DATE_ADD(cycleDateDue, INTERVAL 15 DAY) AS ReminderCallDate1,
DATE_ADD(cycleDateDue, INTERVAL 30 DAY) AS SuspendLetterDate, /*A calculated
date*/
DATE_ADD('SuspendLetterDate', INTERVAL 12 DAY) AS AccountSuspendDate
/*Attempt to calculate against that calculated date*/
from tblBillCycle;

TIA!

Jay