src/Expression.php
public function getOne()
    {
        $data = $this->getRow();
        if (!$data) {
            throw new Exception([
                'Unable to fetch single cell of data for getOne from this query',
                'result' => $data,
                'query'  => $this->getDebugQuery(),
            ]);
        }
        $one = array_shift($data);

        return $one;
    }
public function getOne()
    {
        $data = $this->getRow();
        if (!$data) {
            throw new Exception([
                'Unable to fetch single cell of data for getOne from this query',
                'result' => $data,
                'query'  => $this->getDebugQuery(),
            ]);
        }
        $one = array_shift($data);

        return $one;
    }
Executes expression and return first value of first row of data from result-set.

@return string