Concerns when creating a synchronisation script?

[Cep]

Hi,

 

I was just wondering if people could put forward some points on what I should keep in consideration when writing a php script that will synchronise a MySQL database with an Access database (and visa versa).

 

I am writing a script at this moment and I just wanted to know if anyone could give me some things to look out for when coding such a script? For example, does the record already exist? Check to see if a duplicate has been created? etc etc