src/Database.php
public function selectCol(string $sql, array $parameters = [])
    {
        $statement = $this->select($sql, $parameters);

        if ($statement === null) {
            return false;
        }

        $datas = $this->readAll($statement);
        $col = [];
        foreach ($datas as $data) {
            $col[] = \current($data);
        }

        $statement->closeCursor();
        $statement = null;

        return $col;
    }
public function selectCol(string $sql, array $parameters = [])
    {
        $statement = $this->select($sql, $parameters);

        if ($statement === null) {
            return false;
        }

        $datas = $this->readAll($statement);
        $col = [];
        foreach ($datas as $data) {
            $col[] = \current($data);
        }

        $statement->closeCursor();
        $statement = null;

        return $col;
    }
@param string $sql
@param array  $parameters

@throws DatabaseException

@return array|bool