$this select(array|mixed $columns = array('*')) Set the columns to be selected

Builder|

bool isExpression(mixed $value) Determine if the given value is a raw expression

string wrap(Expression|string $value, bool $prefixAlias

string getValue(Expression $expression)

bool isExpression(mixed $value) Determine if the given value is a raw expression

array processColumnListing(array $results) Process the results of a column

Builder|

array processSelect(Builder $query, array $results)

mixed max(string $column) Retrieve the maximum value of a given column