bp_document :: get_activity_attachment_id（整数$ activity_id.的）

公共静态函数get_actity_attachment_id（$ activity_id = 0）{global $ bp，$ wpdb;if（空（$ activity_id））{返回false;}返回（int）$ wpdb-> get_var（从{$ bp-> document-> table_name} d中选择distinct d.attachment_id d.actity_id = {$ activity_id}）;}