match event windows (in month) using sas sql - sql

Question

I have two files, one with event date, the other one is the security prices I need to match the month with event month 0, -1 (previous month), and +1 (the month after event month). So e.g., one observation has event date 1/1/2010, I have the daily bond prices from 1/1/2009 to 1/20/2010, but I need to match January,2010 to December 2009 prices and February 2010. I have the following codes to do that,
PROC SQL;
CREATE TABLE test AS
select *
FROM bondprice as a, sdc as b
where b.Participant_CUSIP=a.cusip
& INTCK('MONTH',b.Alliance_Date,a.time)>=-1
& INTCK('MONTH',b.Alliance_Date,a.time)<=1 ;
QUIT;
DATA test1;
SET test;
BY deal_number CUSIP code time;
IF first.code THEN price1=price;
IF first.code THEN day1=time;
IF last.code THEN price0=price;
IF last.code THEN day0=time;
RUN;
clearly this observation should be only matched in 1-month Jan 2010 (0,0) and 2-month Dec 2009 to Jan 2010 (-1,0), because it does not have 3-month Feb 2010's prices. However, if using my codes above, it will yield as a valid obs who has 3-month price since it fell into the range of >=-1 and <=1.
So the first part of code is not accurate (the >= and <= range): it yields any prices that falls into December 2009 to Feb 2010, this is wrong because of two situations. First, if the bond prices stops in between Dec 2009 and Jan 2010, it will be counting as a valid 2-month and 3-month observations. Second, if the bond prices begins in between Jan 2010 and Feb 2010, it will be counting as a valid 3-month observation. Both of these two situation will yield invalid observations, since the first situation do not have Feb 2010 prices but still counts as 2-month and 3-month, and the second situation do not have either Dec 2009 or Jan 2010 prices, but still counts as 3-month.
Will someone help me with this? How can I modify the code so that the 3-month window and 2-month window contains the relative months?
I hope I describe the problem clearly. Please let me know if anything is unclear.
I've uploaded an example to this problem here.
https://www.dropbox.com/s/hx9ahst7nts4k0q/ex1.xlsx?dl=0