exporting MYSQL fectched row into csv in php - php

Question

Following is a part of my php program which is written to fetch rows from mysql table from input IDs. But I wanted to get the result directly to '.csv' file. I know php has built in function for that, but I could not include it effectively. So can anyone give a direction for export to csv using advanced php function?
$file = fopen("fetched.csv","w");
for($i=0;$i<=$len;$i++)
{
$lo = $locus[$i];
mysqli_select_db($conn,"microarray");
$query = mysqli_query("SELECT * FROM anatomy WHERE locus_id = "$lo"");
while ($row = mysqli_fetch_row($query))
{
}
}

Answer 1

You don't necessarily need an "advanced php function". A csv file is just a sequence of comma separated columns. Try this out.
function addRowToCsv(& $csvString, $cols) {
$csvString = implode(',', $cols) . PHP_EOL;
}
$csvString = '';
$first = true;
while ($row = mysqli_fetch_assoc($query)) {
if ($first === true) {
$first = false;
addRowToCsv($csvString, array_keys($row));
}
addRowToCsv($csvString, $row);
}
header('Content-type: text/csv');
header('Content-disposition: attachment;filename=MyCsvFile.csv');
echo $csvString;
Notice that the first argument to addRowToCsv is passed by reference. This is not required and you could easily use a return value, but this is just how I would do it.
-- Edit --
I just noticed you are saving the output to a file rather than serving it as a download. If that is what you want to do then use the above but replace
header('Content-type: text/csv');
header('Content-disposition: attachment;filename=MyCsvFile.csv');
echo $csvString;
With..
file_put_contents('MyCsvFile.csv', $csvString);