file handling ....!

in one of my project ,150 to 200 customers r there. .and i have to maintain record of each. There r 3 separate programs on separate machine to update that records.
So options in front of me r:
1 “to maintain 1 file and store all records in the same file” or
2 “maintain separate 150 or 200 files..(each file for each person) “

Requirement:(Security is more imp. Than the accuracy )

so tell me which one is feasible.. and at minimum risk.


My second ques is : Is it possible that 2 programs can simultaneously update records from same file?
Both problems r related to C.

Your first problem is more complicated than you think. If you have a single file, on which machine does it reside, if you have 150-200, where do they reside?

In general, security issues are easiest to solve by having a single file store application on a server machine and multiple distributed clients performing updates. If you have a server process managing access to your file/s the actual structure of your file/s is transparent to the application clients, (good if you wish to change it later!).

Your second question, yes, but it can be risky. It depends how much security you need and how much work you are prepared to do. You need to do your own record level locking. A standard DB package will allow you to do what you want if you have access to one.