SQL SIMPLE

My Sql:
SELECT ACCT_NBR, ALI_JOIN_DT, TO_CHAR(ALI_JOIN_DT, 'YYYYMM') -1
FROM ACCT
WHERE ACCT_NBR = 117

My result:
ACCT_NBR      ALI_JOIN_DT      TO_CHAR(ALI_JOIN_DT,'YYYYMM')-1      
117      12/10/2009 00:00:00      200911      
                  
NOW I WANT TO ADD ONE MORE COLUMN TO MY SQL , AS BELOW, so that I can find the month of year of 12 months before ali_join_dt                  
ACCT_NBR      ALI_JOIN_DT      TO_CHAR(ALI_JOIN_DT,'YYYYMM')-1      NEW column
117      12/10/2009 00:00:00      200911      200812