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Dynamically bind mysqli_stmt parameters and then bind result (PHP)

can any one help me on how could I create a dynamic bind_result on PHP.
My query field doesn’t know how many fields are there since it was created dynamically (e.g creating year fields base on the date range). below is my script and highlighted on where is the problem.

public function getMarketingReports($datefrom,$dateto)
    {
        $yearfrom = date("Y", strtotime($datefrom));
        $yearto = date("Y", strtotime($dateto));

        //create year fields
        $concatYear = "";
        for($year=$yearfrom;$year<=$yearto;$year++){
            $concatYear .= "SUM(IF(c.datecreated='".$year."',IF(LOWER(c.fullTimeEployeeType)='basic hour rate', c.fullTimeEployeeTypeAmount*2080 , c.fullTimeEployeeTypeAmount),0)) ".$year.",";
        }


        $reportdata = array();
        $db = Connection::Open();
        $stmt = $db->stmt_init();
        if($stmt->prepare("SELECT p.Code `PositionCode`,
                                  p.name `PositionName`,
                                  l.value `Location`,
                                  ".$concatYear."
                                  SUM(b.field205) `TotalEmployees`
                             FROM c1 c
                            INNER JOIN b1 b
                               ON c.registrationid=b.id
                            INNER JOIN positions p
                               ON c.positionid=p.id
                            INNER JOIN lookupvalues l
                               ON c.location=l.id
                            WHERE c.`status`!=2
                              AND c.datecreated BETWEEN ? AND ?
                            GROUP BY c.positionid,c.location,YEAR(c.datecreated)")){

            $datefrom = $datefrom." 00:00:00";
            $dateto = $dateto." 23:59:59";
            $stmt->bind_param("ss",$datefrom,$dateto);
            $stmt->execute();
            $stmt->bind_result
            (
                $positionCode,
                $positionName,
                $location,

                **//getting bind result data here for year fields**

                $totalEmployees
            );
            while($stmt->fetch())
            {
                $surveydata = array();
                $surveydata['positionCode'] = $positionCode;
                $surveydata['positionName'] = $positionName;
                $surveydata['location'] = $location;

                **//storing of data here for year fields**

                $surveydata['totalEmployees'] = $totalEmployees;
                array_push($reportdata,$surveydata);
            }
        }
        Connection::Close();
        return $reportdata;

    }

Is it possible? Can anyone help me on how could I solve this problem

Answer 1

To start, your code that generates the year fields has a nice syntax error:

"SUM(IF(c.datecreated='".$year."',IF(LOWER(c.fullTimeEployeeType)='basic hour rate', c.fullTimeEployeeTypeAmount*2080 , c.fullTimeEployeeTypeAmount),0) ".$year.","

The SUM( opening statement is missing a closing parentheses. On top of that, you have a floating ".$year." that isn’t part of any of the enclosed methods (though, it could be used as an alias; I’m not used to seeing it without a preceeding AS though – so this could be my mistake). To take a guess, I would say to replace the ".$year." with a ) and that should fix that part:

$concatYear .= "SUM(IF(c.datecreated='".$year."',IF(LOWER(c.fullTimeEployeeType)='basic hour rate', c.fullTimeEployeeTypeAmount*2080 , c.fullTimeEployeeTypeAmount),0)),";

If the $year addition is in fact to be an alias, you could add the closing parentheses immediately before it to close the SUM() function.

Regarding dynamically binding the variables, my ideal solution actually comes from a similar question/answer on SO (this is a direct copy/paste and I take no credit for it, but I do like it =P):

    // Get metadata for field names
    $meta = $stmt->result_metadata();

    // This is the tricky bit dynamically creating an array of variables to use
    // to bind the results
    while ($field = $meta->fetch_field()) { 
        $var = $field->name; 
        $$var = null; 
        $fields[$var] = &$$var;
    }

    // Bind Results
    call_user_func_array(array($stmt,'bind_result'),$fields);

    // Fetch Results
    $i = 0;
    while ($stmt->fetch()) {
        $results[$i] = array();
        foreach($fields as $k => $v)
            $results[$i][$k] = $v;
        $i++;
    }