stata 10 question

#1
I am working with Stata 10. I have two datasets, dataset 1 has most of the variables I want, and has one date (that I want) for each observation (meaning each observation has one date that is not the same as the other observations). Dataset 2 has 2 versions of several variables coded as 0,1 that I want (lets call them A1 A 2 B1 B 2 C1 C 2 etc…). There are multiple dates for each observation in dataset 2 (including my date of interest- the date that I am using for each observation in dataset1….which again, is a different date for each observation). What I would like to do is merge together the two datasets, and get rid of any data on A1 A 2 B1 B 2 C1 C 2 (etc…) that occurs after the date of interest (for each observation), and then create one variable for A (for example) coded as 1 if A1 or A2 ever equals 1 (on my date of interest or any date before my date of interest) (otherwise it will be 0), and create one variable B coded as 1 if B1 or B2 ever equals 1 (on my date of interest or any date before my date of interest)….and so on, for all of those variables… (after I create A, B, C etc...coded as 0,1 based on my adding together all the A1s and A2s before and including my date of interest, I want to also get rid of all the dates before my date of interest, because I don't need any info from those dates except for the initial info on A1 A2 etc in order to create my A variable- which I will just put in with the data for my date of interest).

I am not sure what the order should be, in order to accomplish this- do I merge first, so that I will know the date of interest? How do I get rid of all the observations after the date of interest? How do I add up all of the As (A1s and A2s) to get my 0 or 1 (0 is if all the A1s and A2s up to and including my date of interest equal 0…otherwise its 1)? When I'm done with that, how do I get rid of all of the data from the other dates (before my date of interest)?

Thanks!!!