remote mysql queries without direct access

[abazoskib]

what is the best way to allow multiple customers to insert data into my database without giving them a direct connection into my db? ive read so much about soap, rest, and xml-rpc, and i still have no idea what to choose. basically, the customers have registrations of users that need to be sent to my database for marketing purposes. there could potentially be many, many customers to deal with, so i want to make this a web service where i could send analytical information back(future plan). what should i choose?

[abazoskib]

and i forgot, MORE IMPORTANTLY, whatever method is best, where can i look to for a guide or tutorial? i need a pretty solid tutorial if im gonna learn this

[Danny620]

well i think the best method would be as following

 

create a sign up page

then a log in page

make levels like e.g 1= member 2=staff 3=admin

then the people you allow to insert member into the database set there level to like 2 and that will allow them to go to a page called, members where it contains a few forms on information you want to insert into the database about that member 

[abazoskib]

no, its not that simple. my clients are people with their own websites on which other people register. i need this same registration info passed to my database without giving them direct access.