Method: Sequel::Dataset#window_sql_append

Defined in:
lib/sequel/dataset/sql.rb

#window_sql_append(sql, opts) ⇒ Object

Append literalization of windows (for window functions) to SQL string.

Raises:

[View source]

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# File 'lib/sequel/dataset/sql.rb', line 788

def window_sql_append(sql, opts)
  raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
  space = false
  space_s = ' '

  sql << '('

  if window = opts[:window]
    literal_append(sql, window)
    space = true
  end

  if part = opts[:partition]
    sql << space_s if space
    sql << "PARTITION BY "
    expression_list_append(sql, Array(part))
    space = true
  end

  if order = opts[:order]
    sql << space_s if space
    sql << "ORDER BY "
    expression_list_append(sql, Array(order))
    space = true
  end

  if frame = opts[:frame]
    sql << space_s if space

    if frame.is_a?(String)
      sql << frame
    else
      case frame
      when :all
        frame_type = :rows
        frame_start = :preceding
        frame_end = :following
      when :rows, :range, :groups
        frame_type = frame
        frame_start = :preceding
        frame_end = :current
      when Hash
        frame_type = frame[:type]
        unless frame_type == :rows || frame_type == :range || frame_type == :groups
          raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
        end
        unless frame_start = frame[:start]
          raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
        end
        frame_end = frame[:end]
        frame_exclude = frame[:exclude]
      else
        raise Error, "invalid window :frame option: #{frame.inspect}"
      end

      sql << frame_type.to_s.upcase << " "
      sql << 'BETWEEN ' if frame_end
      window_frame_boundary_sql_append(sql, frame_start, :preceding)
      if frame_end
        sql << " AND "
        window_frame_boundary_sql_append(sql, frame_end, :following)
      end

      if frame_exclude
        sql << " EXCLUDE "

        case frame_exclude
        when :current
          sql << "CURRENT ROW"
        when :group
          sql << "GROUP"
        when :ties
          sql << "TIES"
        when :no_others
          sql << "NO OTHERS"
        else
          raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
        end
      end
    end
  end

  sql << ')'
end