Suppose that I've a website where I'm offering the user to link his social network accounts like facebook, twitter, ... with his account on my website. Now I'm supporting facebook and twitter in the website, but later I'll add more. So currently I've a table in the database for each supported social network, for example Facebook table which will have the facebook user id and the security hash and whatever I need in the app. this table has a foreign key user id to the User table for users in the website. Now suppose that I want to know for each user which social networks are linked with my website, so I decided to add a column to the user table of varchar. And I'll have a sequence in it, for above example, if the user is linking both facebook and twitter account, the value will be '11', if he is linking facebook only, the value would be '10' and so on. Is this a good way to design such thing?
Also when I want to support a new social network say Google+, all I've to do is to add a table GooglePlus table in the database, and then write a script which will add a char to the existing column, initially all users will have whatever they had before + '0'. So the first user will have '110' and the second user will have '100'. And so on.
Is this the best approach I can follow in this situation? Is this a maintainable design?
An example to clarify the question:
The user table:
User_Id LinkedSocialNetworks 1 '100' 2 '101'
each char in the linked social networks represents a flag either this user is linking (1) his account with a specified social network or not (0). I know as the developer of the app is that the first char is for facebook, second is for twitter, Google+, ....
From inspecting the user table, I know that user 1 is linking his account with Facebook, user 2 is linking with Facebook and google + but not with twitter.
After getting this information, for user 1, I'll get his information from Facebook table only, for user 2, I'll get his information from Facebook table and Google+.
I'm using MySql by the way