walkSelectClause example

class ForceIndexWalker extends SqlWalker
{
    public const HINT_FORCE_INDEX = 'ForceIndexWalker.ForceIndex';

    public const HINT_STRAIGHT_JOIN = 'StraightJoinWalker.StraightJoin';

    public const HINT_SQL_NO_CACHE = 'SqlNoCacheWalker.SqlNoCache';

    public function walkSelectClause($selectClause)
    {
        $sql = parent::walkSelectClause($selectClause);

        if ($this->getQuery()->getHint(self::HINT_SQL_NO_CACHE) === true) {
            if ($selectClause->isDistinct) {
                $sql = str_replace('SELECT DISTINCT', 'SELECT DISTINCT SQL_NO_CACHE', $sql);
            } else {
                $sql = str_replace('SELECT', 'SELECT SQL_NO_CACHE ', $sql);
            }
        }

        if ($this->getQuery()->getHint(self::HINT_STRAIGHT_JOIN) === true) {
            $sql = str_replace('SELECT', 'SELECT STRAIGHT_JOIN ', $sql);
        }