mysql - display select options based on value exists in database -

<%= form_for(@timetable) |f| %>      <% timetable.all.each |t| %>       <% if t.day == "monday" %>         <%= f.select :day, options_for_select(%w[tuesday wednesday thursday friday saturday sunday]) %>       <% elsif t.day == "tuesday" %>         <%= f.select :day, options_for_select(%w[wednesday thursday friday saturday sunday]) %>       <% elsif t.day == "wednesday" %>         <%= f.select :day, options_for_select(%w[thursday friday saturday sunday]) %>       <% elsif t.day == "thursday" %>         <%= f.select :day, options_for_select(%w[friday saturday sunday]) %>       <% elsif t.day == "friday" %>         <%= f.select :day, options_for_select(%w[saturday sunday]) %>       <% elsif t.day == "saturday" %>         <%= f.select :day, options_for_select(%w[sunday]) %>       <% else %>         <%= f.select :day, options_for_select(%w[monday tuesday wednesday thursday friday saturday sunday]) %>       <% end %> <% end %> <% end %> 

if value "monday" exits in database field "day" value "monday" should not appear in select options. there other efficient way this?

got answer

<% @values = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"] %> <%= f.select :day, options_for_select(@values - timetable.pluck(:day)) %> 

<% values = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"] %> <%# timetable.all.each |t| %>         <%= f.select :day, options_for_select(values - [@timetable.day], selected: @timetable.day ) %> <%# end %> 

i comment out looping there showing multiple select box.