class AddUniqueIndexOnMembers < ActiveRecord::Migration def self.up # Clean and reassign MemberRole rows if needed MemberRole.delete_all("member_id NOT IN (SELECT id FROM #{Member.table_name})") MemberRole.update_all("member_id =" + " (SELECT min(m2.id) FROM #{Member.table_name} m1, #{Member.table_name} m2" + " WHERE m1.user_id = m2.user_id AND m1.project_id = m2.project_id" + " AND m1.id = #{MemberRole.table_name}.member_id)") # Remove duplicates Member.connection.select_values("SELECT m.id FROM #{Member.table_name} m" + " WHERE m.id > (SELECT min(m1.id) FROM #{Member.table_name} m1 WHERE m1.user_id = m.user_id AND m1.project_id = m.project_id)").each do |i| Member.delete_all(["id = ?", i]) end # Then add a unique index add_index :members, [:user_id, :project_id], :unique => true end def self.down remove_index :members, [:user_id, :project_id] end end