code: function (column, cb) {
              var ret = new Promise();
              this.__aggregateDataset()
                  .select(sql.min(this.stringToIdentifier(column)).as("v1"), sql.max(this.stringToIdentifier(column)).as("v2"))
                  .first()
                  .chain(function (r) {
                      ret.callback(r.v1, r.v2);
                  }, ret.errback);
              return ret.classic(cb).promise();
          }
docs: Returns a promise resolved with  a range from the minimum and maximum values for the
  given column.
  
  @example
  // SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
  DB.from("table").range("id").chain(function(min, max){
  //e.g min === 1 AND max === 10
  });
  
  @param {String|patio.sql.Identifier} column the column to find the min and max value for.
  @param {Function} [cb] the callback to invoke when the action is done.
  
  @return {comb.Promise} a promise that is resolved with the min and max value, as the first
  and second args respectively.