Avoiding code repetition for MySQL queries (multiple while) - php

Question

I have the following code:
<?php
include_once "connect.php";
$question_01 = mysqli_real_escape_string($con, $_POST['question_01']);
// $question_02 - $question_09 go here...
$question_10 = mysqli_real_escape_string($con, $_POST['question_10']);
$i = 0;
$array_sum=[];
while ($i < 10){
$i++;
$sql = "SELECT * FROM parteners WHERE question_no = 1 AND answer_variant = '$question_01'";
$result = mysqli_query($con, $sql);
$final_array_1 = array();
while ($row = mysqli_fetch_array($result, MYSQLI_NUM))
{
$final_array_1 = $row;
$array_sum = array_map(function () {
return array_sum(func_get_args());
}, $array_sum, $final_array_1);
}
}
print_r($final_array_1);
As you can see, I need to repeat the code for each $question_##. Is there a smarter way of doing this other than repeating the code? I'm not only concerned about turning everything into a code spaghetti but also about the efficiency of the operations as in loading times.
Let me know if you need clarification.
Update: Basically it should increase the value of "question_no" in the query until it reaches 10 and pick the corresponding $_POST value for each question.

Answer 1

There are two ways, variable variables or arrays. I'd suggest arrays as they are less prone to throwing errors everywhere.
<?php
include_once "connect.php";
$questions = array();
$questions[1] = mysqli_real_escape_string($con, $_POST['question_01']);
// $question_02 - $question_09 go here...
$questions[10] = mysqli_real_escape_string($con, $_POST['question_10']);
$i = 0;
$array_sum=[];
while ($i < 10){
$i++;
$sql = "SELECT * FROM parteners WHERE question_no = $i AND answer_variant = '".$questions[$i]."'";
$result = mysqli_query($con, $sql);
$final_array_1 = array();
while ($row = mysqli_fetch_array($result, MYSQLI_NUM))
{
$final_array_1 = $row;
$array_sum = array_map(function () {
return array_sum(func_get_args());
}, $array_sum, $final_array_1);
}
}
print_r($final_array_1);
EDIT: The reason I used an array instead of just straight up using the POST variable in the while loop is so there is room before you run anything for validation (ensuring your question array contains 10 posted values etc)

Answer 2

I would build one SQL-Statement which contains all questions and anwsers and do the rest with programming logic. SQL-Queries in a loop are a bad idea, because you have to do a lot of overhead for getting a task done, which the database server can do better. Also you should use prepared statements for performance and security.
$query = "SELECT * FROM parteners WHERE (question_no = 1 AND answer_variant = ?) OR (question_no = 2 AND answer_variant = ?) OR (question_no = 3 AND answer_variant = ?) OR (question_no = 4 AND answer_variant = ?) OR (question_no = 5 AND answer_variant = ?) OR (question_no = 6 AND answer_variant = ?) OR (question_no = 7 AND answer_variant = ?) OR (question_no = 8 AND answer_variant = ?) OR (question_no = 9 AND answer_variant = ?) OR (question_no = 10 AND answer_variant = ?)"
$stmt = myqli_prepare($query);
mysqli_stmt_bind_param($stmt, 'ssssssssss', $question_01, $question_02, $question_03,.....);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

Answer 3

First, to make your code modern and efficient, you should be using PHP
Data Objects, or PDO for short. You will have access to prepared
statements, which are made exactly for this: you build a query
"template" and execute with different data, very efficiently and secure.
The loop is the proper way to do it. Also, your $questions array is a
bit unecessary since you can retrieve data from $_POST right inside
your loop. But if you want to use it, there is no need to "escape" the
string for the database, since it's handled by PDO. So you can build
your array in a easier way:
$questions = [
$_POST['question_01'],
$_POST['question_02'],
$_POST['question_03'],
# ...
$_POST['question_10'],
];
Your loop with PDO:
$dbh = ... # create your database handle, connect to it
$st = $dbh->prepare("
SELECT * FROM parteners
WHERE question_no = ? AND answer_variant = ?;
");
foreach (range(1, 10) as $i) {
$result = $st->execute([ $i, $questions[$i-1] ]);
# or, to build directly
$result = $st->execute([
$i, $_POST[ sprintf("question_%02d", $i) ]
]);
$final_array[] = $result->fetchAll(PDO::FETCH_NUM);
}
print_r($final_array);