Mysql: How can I structure a table to hold usernames of various social networks? -

i want store social network usernames each of site's users. how can structure table hold names of social network sites along username given site?

users     id     first_name     last_name  profiles     fk_users_id     country  social_networks     id     name  social_accounts ?     fk_users_id ? 

i think should create new relation table.and create social_accounts keep relation table_id fk.

socialnetworks_user_relation ---------------------------- relation_id     user_id (fk_user_id) network_id(fk_socialnetwork_id)    social_accounts -----------------     relation_id(fk_socialnetworks_user_relation) account_uname account_pass 

hope you.