Insert values into custom field's extra columns in database I'm new to drupal 7.

I've create a custom field with extra columns via field api, and create the field well(via UI), but I can't "save" it while using the field.

I've google for it and found some keywords like

hook_field_storage_write()、hook_field_attach_submit()


But still can't get what I want.
Can someone give me advices?
Can you provide more details how did you implement schema, widget, formatter etc.
I guess this link can be helpful for you http://www.slideshare.net/zugec/fields-in-core-how-to-create-a-custom-field