Im working with users profiles DB structure with Sequelize/NodeJS/MySQL. I stoped at point where i have to make tables with relation and moiddle table needs to have some important value.

User
id, name, surname

Users_socials
id, userId, socialId, url

Socials
id, name, prefix

Now I have this:

db.social.belongsToMany(db.user, {
  through: "user_socials",
  foreignKey: "socialId",
  otherKey: "userId"
});
db.user.belongsToMany(db.social, {
  through: "user_socials",
  foreignKey: "userId",
  otherKey: "socialId"
});

How to build structure for setting the url in users_socials and to getting the users by social id or name and socials by user id or name.