<%= select_tag "enterprise_id", options_from_collection_for_select(@enterprises, "id", "name"), class: 'my_select', style: 'width: 280px;

<%= select_tag "enterprise_id", options_from_collection_for_select(@enterprises, "id", "name"), :include_blank => '全部', class: 'my_select', style: 'width: 280px;