I would like to migrate custom user fields from an external USER database table to the custom tables of Drupal 7.
I created custom fields for my users (First Name, Last Name, ...) under administration/configuration/account settings and I can confirm that these fields are created if I go to administration/people/ and click "edit" next to each user.
I also know that for each individual custom field that I have created, D7 created a new table of the form "field_data_field_[FIELD_NAME]" (ie. field_data_field_first_name, field_data_field_last_name, ...)
The specific commands I would like to find more information about are:
MigrateDestinationUser::getKeySchema(); $this->destination = new MigrateDestinationUser();
I understand the above command is the default used to import users to the default "users" database.
How can I migrate my content to another D7 table? Such as migrating the First Name from the external table to field_data_field_first_name?