PHP: Creating a MYSQL query inside a function - php

Question

I have a function which performs an SQL query, "queryValue" the actual query to perform is passed later.
Function queryCreate($queryValue){
//DB connection variables
$host = "";
$user = "";
$password = "";
$database = "";
//create the connection
$conn = new mysqli($host, $user, $password, $database);
if ($conn->connect_error) {
die('DB Connection error: (' . $conn->connect_error . ') ' . $conn->connection_errorno);
}
$query = mysqli_query($conn,$queryValue) or die(mysqli_error($conn));
if ($result = mysqli_fetch_array($query,MYSQLI_ASSOC)) {
fputcsv($fh, array_keys($result));
fputcsv($fh, $result);
while ($result = mysqli_fetch_array($query,MYSQLI_ASSOC)) {
fputcsv($fh, $result);
}
}
return $queryValue;
}
I'm then attempting to assign the query value in a separate if statement. Below:
if(isset($_POST["Submit"]) && ($_POST['Weight'] == 'Weight')) {
$fh = csvCreate("Output Weight Null ".date('m-d-Y-His').".csv");
$queryValue = queryCreate('SELECT * FROM `table` WHERE WEIGHT = 0 OR weight IS NULL');
}
The problem I have is that the query does not appear to be being passed to the function. Could anyone suggest where I have gone wrong here? Many thanks.
The csvCreate function is shown here:
function csvCreate($filename){
header("Cache=Control: must-revalidate, post-check=0, pre-check=0");
header('Content-Description: File Transfer');
header("Content-type: text/csv");
header("Content-Disposition: attachment; filename={$filename}");
header("Expires: 0");
header("Pragma: public");
$fh = #fopen( 'php://output', 'w' );
return $fh;
}

Answer 1

The problem is with the parameters of fputcsv() calls within queryCreate() function.
The file handler ($fh variable) is declared outside of queryCreate() function using the csvCreate() function:
$fh = csvCreate("Output Weight Null ".date('m-d-Y-His').".csv");
However,$fh is not passed as a parameter to queryCreate(), nor is $fh declared as a global variable, yet $fh variable is used to reference the file in all fputcsv() calls:
fputcsv($fh, array_keys($result));
In this case, $fh within queryCreate() will not refer to $fh variable where queryCreate() is called, but it will create a local $fh variable (empty at that), therefore the fputcsv() call will fail. The csv file is created in csvCreate(), this is independent from putting the values within the file.
The best solution would be to either pass $fh as a parameter to queryCreate(), or call csvCreate() from queryCreate(). In the latter case, the name of the dataset should be passed as a parameter.
UPDATE
Let's see some code as well:
//declaration of queryCreate()
Function queryCreate($queryValue, $reportName){ //$reportName is the name of the report
...
//create the csv file, put some parameter checks here as well
$fh = csvCreate($reportName.date('m-d-Y-His').".csv");
//and some error handling here
...
//output the contents of the query to the csv file
if ($result = mysqli_fetch_array($query,MYSQLI_ASSOC)) {
fputcsv($fh, array_keys($result));
fputcsv($fh, $result);
while ($result = mysqli_fetch_array($query,MYSQLI_ASSOC)) {
fputcsv($fh, $result);
}
}
... //should include closing of the csv file
} //end queryCreate()
...
//call the queryCreate()
if(isset($_POST["Submit"]) && ($_POST['Weight'] == 'Weight')) {
$queryValue = queryCreate('SELECT * FROM `table` WHERE WEIGHT = 0 OR weight IS NULL','Output Weight Null ');
}