在您的SQL语法中存在错误；请检查与您的MariaDB服务器版本相对应的手册，以查找在第6行附近使用正确语法的方法
    SELECT 
        `instrument`.`id` as `id`, 
        `instrument`.`name` as `name`, 
        `price`, 
        `isix`, 
        `wkn`, 
        `isin`, 
        `instrument`.`account` as `accID`, 
        `own_invest`, 
        `interest`, 
        (select company 
            from chart_of_accounts 
            where chart_of_accounts.id = accID 
            group by company
        ) as company_id, 
        (select url 
            from company 
            where company.id = company_id
        ) as company_url, 
        `tiv_bond_type`.`name` as `bond_type` 
    FROM 
        `instrument` 
    LEFT JOIN `bond` ON `bond`.`instrument` = `instrument`.`id` 
    LEFT JOIN `tiv_bond_type` ON `tiv_bond_type`.`bond_type` = `bond`.`type` 
    WHERE 
        ( ) AND 
        `instrument`.`type` = 2 
    ORDER BY 
        `instrument`.`price` DESC LIMIT 100
文件名：models/Search_model.php
行号：251
public function search_bonds($name, $isin, $isix, $wkn, $type, $initial_price, $end_price, $initial_interest, $end_interest) {
        $bond_name = explode(" ", $name);
        $this->db->select("instrument.id as id, instrument.name as name, price, isix, wkn, isin, instrument.account as accID, own_invest, interest,
                            (select company from chart_of_accounts where chart_of_accounts.id = accID group by company) as company_id,
                            (select url from company where company.id = company_id) as company_url,
                            tiv_bond_type.name as bond_type");
        $this->db->from("instrument");
        $this->db->join("bond", "bond.instrument = instrument.id", "left", "outer");
        $this->db->join("tiv_bond_type", "tiv_bond_type.bond_type = bond.type", "left");
        if (strlen($isin) > 3)
            $this->db->where("instrument.isin", $isin);
        if (strlen($name) > 1) {
            $this->db->group_start();
            $this->create_search_permutations($bond_name, 1);
            $this->db->group_end();
        }
        if (strlen($isix))
            $this->db->where("instrument.isix", $isix);
        if (strlen($wkn) > 3 )
            $this->db->where("instrument.wkn", $wkn);
        if (strlen($type) && is_numeric($type))
            $this->db->where('bond.type', $type);
        if (is_numeric($initial_price) && is_numeric($end_price)) {
            $this->db->group_start();
            $this->db->where("instrument.price >=", $initial_price);
            $this->db->where("instrument.price <=", $end_price);
            $this->db->group_end();
        }
        else if (is_numeric($initial_price) && ! is_numeric($end_price))
            $this->db->where("instrument.price >=", $initial_price);
        else if (is_numeric($end_price)  && ! is_numeric($initial_price))
            $this->db->where("instrument.price <=", $end_price);
        if (is_numeric($initial_interest) && is_numeric($end_interest)) {
            $this->db->group_start();
            $this->db->where("bond.interest >=", $initial_interest);
            $this->db->where("bond.interest <=", $end_interest);
            $this->db->group_end();
        }
        else if (is_numeric($initial_interest) && ! is_numeric($end_interest))
            $this->db->where("bond.interest >=", $initial_interest);
        else if (is_numeric($end_price)  && ! is_numeric($initial_interest))
            $this->db->where("bond.interest <=", $end_interest);
        $this->db->where("instrument.type", 2);
        $this->db->order_by("instrument.price", "desc");
        $this->db->limit(100);
        return $this->db->get()->result_array();
    }
    private function create_search_permutations($search_array, $table_name, $permutations = array()) {
        /*
            $query_type变量定义了查询字符串所针对的表列类型
            即$query_type == 1定义查询字符串是为了instrument.name，$query_type == 2是为了company.name
        */
        if (empty($search_array)) {
            if ($table_name == 'instrument')
                $this->db->or_where("instrument.name like '%" . join('%', $permutations) . "%'");
            elseif ($table_name == 'company')
                $this->db->or_where("company.name like '%" . join('%', $permutations) . "%'");
            else
                return;
        }
        else {
            for ($iterator = count($search_array) - 1; $iterator >= 0; --$iterator) {
                $new_search_array = $search_array;
                $new_permutations = $permutations;
                list($key) = array_splice($new_search_array, $iterator, 1);
                array_unshift($new_permutations, $key);
                $this->create_search_permutations($new_search_array, $table_name, $new_permutations);
            }
        }
    }