PHP Mysqli select to csv Options

[nuddernuby]

Could someone save me from insanity and provide a working script for the following simple problem, please. (I've tried many and failed)

I have a table 'projects' with field 'projectname', currently populated with five records, say A,B,C,D & E.
I need to store an the array of these records in this format: $arr=("A","B","C","D","E") or output it to a csv string in csv file.

I can echo the results but fail to get this into the required format/file.

Basic query is:
$query=mysqli_query($conn,"SELECT projectname FROM projects");

What then?

Apologies for the simplicity of the problem.

[nuddernuby]

Thank you, I finally managed to get it working using this simple script with $proj as the required output:

$query = "SELECT * FROM `projects` WHERE co='ABC' ";
$result = mysql_query($query);
$number = mysql_numrows($result);
$x = 0;
$proj = array();
while ($x < $number)
{
$row = mysql_fetch_array($result);
$id = $row['id']; $p = $row[ 'projectname' ];
$proj[ $id ] = $p;
$x++;
}
//print_r($proj);
$arr=implode(',',$proj);
//print_r('<br>' . $arr);
file_put_contents('NEWfilename.txt', print_r($proj, true));

So, all well. Thank you for your attention.