Redmine

    class << self

      # Returns true if the database is PostgreSQL

      def postgresql?

      end

      # Returns the PostgreSQL version or nil if another DBMS is used

      # Returns true if the database is MySQL

      def mysql?

      end

      # Returns a SQL statement for case/accent (if possible) insensitive match

        if parent

          previous_root_id = root_id

          self.root_id = parent.root_id

          lft_after_move = target_lft

          self.class.where(:root_id => parent.root_id).update_all([

            "lft = CASE WHEN lft >= :lft THEN lft + :shift ELSE lft END, " +

            "rgt = CASE WHEN rgt >= :lft THEN rgt + :shift ELSE rgt END",

            {:lft => lft_after_move, :shift => (rgt - lft + 1)}

          ])

          self.class.where(:root_id => previous_root_id).update_all([

            "root_id = :root_id, lft = lft + :shift, rgt = rgt + :shift",

            {:root_id => parent.root_id, :shift => lft_after_move - lft}

          ])

          self.lft, self.rgt = lft_after_move, (rgt - lft + lft_after_move)

          parent.send :reload_nested_set_values

        end

      def remove_from_nested_set

        self.class.where(:root_id => root_id).where("lft >= ? AND rgt <= ?", lft, rgt).

          update_all(["root_id = :id, lft = lft - :shift, rgt = rgt - :shift", {:id => id, :shift => lft - 1}])

        self.class.where(:root_id => root_id).update_all([

          "lft = CASE WHEN lft >= :lft THEN lft - :shift ELSE lft END, " +

          "rgt = CASE WHEN rgt >= :lft THEN rgt - :shift ELSE rgt END",

      end

      def lock_nested_set

          lock = "WITH (ROWLOCK HOLDLOCK UPDLOCK)"

          # Custom lock for SQLServer

          # This can be problematic if root_id or parent root_id changes

      def lock_nested_set

        lock = true

          lock = "WITH (ROWLOCK HOLDLOCK UPDLOCK)"

        end

        self.class.order(:id).lock(lock).ids