使call_user_func_array（）与准备好的sql语句一起使用

Question

I have to build up a sql statement and the params from a $place object that has a variable number of properties. When I use prepared sql statements by building the sql statement and params the long and bad practice way it works (returns all the rows from the database that it should):

<?

function buildSQLWhereClause($query, $conn, $place) {
    if ($place['suburb']){
        if($place['city'] && $place['province'] && $place['country']) {
            $query .= "s.country = ? and 
                    s.province = ? and
                    s.city = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ssss", $place['country'], $place['province'], $place['city'], $place['suburb']);
        } else if ($place['province'] && $place['country']) {
            $query .= "s.country = ? and 
                    s.province = ? and
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("sss", $place['country'], $place['province'], $place['suburb']);
        } else if ($place['city'] && $place['province']) {
            $query .= "s.province = ? and
                    s.city = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("sss", $place['province'], $place['city'], $place['suburb']);
        } else if ($place['city'] && $place['country']) {
            $query .= "s.country = ? and
                    s.city = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("sss", $place['country'], $place['city'], $place['suburb']);
        } else if ($place['city']) {
            $query .= "s.city = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['city'], $place['suburb']);
        } else if ($place['province']) {
            $query .= "s.province = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['province'], $place['suburb']);
        } else if ($place['country']) {
            $query .= "s.country = ? and 
                    s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['country'], $place['suburb']);
        } else {
            $query .= "s.suburb = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("s", $place['suburb']);
        }
//////////////////////////// NO SUBURB ///////////////////////////////////////////////////        
    } else if ($place['city']) {
        if ($place['province'] && $place['country']) {
            $query .= "s.country = ? and 
                    s.province = ? and
                    s.city = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("sss", $place['country'], $place['province'], $place['city']);
        } else if ($place['province']) {
            $query .= "s.province = ? and
                    s.city = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['province'], $place['city']); 
        } else if ($place['country']) {
            $query .= "s.country = ? and
                    s.city = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['country'], $place['city']); 
        } else {
            $query .= "s.city = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("s", $place['city']); 
        }
//////////////////////// NO SUBURB OR CITY ////////////////////////////////////////////////////////
    } else if ($place['province']) {
        if ($place['country']) {
            $query .= "s.country = ? and
                    s.province = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("ss", $place['country'], $place['province']); 
        } else {
            $query .= "s.province = ?";

            // prepare and bind
            $stmt = $conn->prepare($query);

            $stmt->bind_param("s", $place['province']); 
        }
//////////////////////////////// NO SUBURB, CITY, OR PROVINCE ///////////////////////////////        
    } else if ($place['country']) {
        $query .= "s.country = ?";

        // prepare and bind
        $stmt = $conn->prepare($query);

        $stmt->bind_param("s", $place['country']); 
    }

    return $stmt;
}

function queryDbForProducts($conn, $place)
{   

    $query = "SELECT p.*, s.* 
            FROM product p 
            INNER JOIN product_shop ps 
            ON ps.p_id = p.p_id 
            INNER JOIN shop s 
            ON s.s_id = ps.s_id 
            WHERE ";

    $stmt = buildSQLWhereClause($query, $conn, $place);

    $stmt->execute();
    $meta = $stmt->result_metadata();

    while ($field = $meta->fetch_field()) {
        $parameters[] =& $row[$field->name];
    }

When I use sql prepared statements by building up the sql statement and params the much better way, it doesn't work:

<?

function buildSQLWhereClause($place) {
    $query = "SELECT p.*, s.* FROM product p INNER JOIN product_shop ps ON ps.p_id = p.p_id INNER JOIN shop s ON s.s_id = ps.s_id WHERE ";
    $queryParams = [];
    $queryParamTypes = "";
    $i = 0;
    $len = count($place);
    foreach ($place as $key => $value) {
        if ($i == $len - 1) {
            $query .= "$key = ?";
            $queryParams[] = $value;
            $queryParamTypes .= "s";
        } else {
            $query .= "$key = ? AND ";
            $queryParams[] = $value;
            $queryParamTypes .= "s";
        }
        $i++;
    }

    return array(
            "query" => $query,
            "queryParams" => $queryParams,
            "queryParamTypes" => $queryParamTypes
        );
}

function queryDbForProducts($conn, $place)
{   
    $queryObject = buildSQLWhereClause($place);
    $query = $queryObject['query'];
    $queryParams = $queryObject['queryParams'];
    $queryParamTypes = $queryObject['queryParamTypes'];


    // prepare and bind
    $stmt = $conn->prepare($query);
    $stmt->bind_param($queryParamTypes, $queryParams); 
    $stmt->execute();
    $meta = $stmt->result_metadata();

Hovering over the $stmt in the debugger shows:

affected_rows:-1
insert_id:0
num_rows:0
param_count:4
field_count:13
errno:2031
error:"No data supplied for parameters in prepared statement"
error_list:array(1)
sqlstate:"HY000"
id:1

No data supplied? Hovering over the $queryParams parameter in the debugger shows:

0:"Grey Lynn"
1:"Auckland"
2:"Auckland"
3:"New Zealand"

So I did provide the query parameters to the $stmt->bind_param() function. Did I provide them in the wrong format?

Hovering over $QueryParamTypes shows:

"ssss"

Hovering over $query shows:

"SELECT p.*, s.* FROM product p INNER JOIN product_shop ps ON ps.p_id = p.p_id INNER JOIN shop s ON s.s_id = ps.s_id WHERE suburb = ? AND city = ? AND province = ? AND country = ?"

How come it works when done with the code at the top of the question and it doesn't work when done with the code without all the is statements?

Answer 1

bind_param does not take an array as an argument, it takes varargs. You will need to use call_user_func_array if you want to call it with a dynamic number of arguments.

ie

$params = array_unshift($queryParams, $queryParamTypes);
call_user_func_array(array($stmt, "bind_param"), $params);

Answer 2

The params passed to call_user_func_array, parameter 2, need to be referenced.

This is the working solution:

    function makeValuesReferenced($arr){
    $refs = array();
    foreach($arr as $key => $value)
        $refs[$key] = &$arr[$key];
    return $refs;
    }

$stmt = $conn->prepare($query);
//$stmt->bind_param($queryParamTypes, $queryParams); 
call_user_func_array(array($stmt, 'bind_param'), makeValuesReferenced($queryParams));
$stmt->execute();

As per this answer

Not knowing about the reference thing mucked me around for a long time. Hope this helps some people.