[php] PHP code to convert a MySQL query to CSV

What is the most efficient way to convert a MySQL query to CSV in PHP please?

It would be best to avoid temp files as this reduces portability (dir paths and setting file-system permissions required).

The CSV should also include one top line of field names.

If you'd like the download to be offered as a download that can be opened directly in Excel, this may work for you: (copied from an old unreleased project of mine)

These functions setup the headers:

function setExcelContentType() {
    if(headers_sent())
        return false;

    header('Content-type: application/vnd.ms-excel');
    return true;
}

function setDownloadAsHeader($filename) {
    if(headers_sent())
        return false;

    header('Content-disposition: attachment; filename=' . $filename);
    return true;
}

This one sends a CSV to a stream using a mysql result

function csvFromResult($stream, $result, $showColumnHeaders = true) {
    if($showColumnHeaders) {
        $columnHeaders = array();
        $nfields = mysql_num_fields($result);
        for($i = 0; $i < $nfields; $i++) {
            $field = mysql_fetch_field($result, $i);
            $columnHeaders[] = $field->name;
        }
        fputcsv($stream, $columnHeaders);
    }

    $nrows = 0;
    while($row = mysql_fetch_row($result)) {
        fputcsv($stream, $row);
        $nrows++;
    }

    return $nrows;
}

This one uses the above function to write a CSV to a file, given by $filename

function csvFileFromResult($filename, $result, $showColumnHeaders = true) {
    $fp = fopen($filename, 'w');
    $rc = csvFromResult($fp, $result, $showColumnHeaders);
    fclose($fp);
    return $rc;
}

And this is where the magic happens ;)

function csvToExcelDownloadFromResult($result, $showColumnHeaders = true, $asFilename = 'data.csv') {
    setExcelContentType();
    setDownloadAsHeader($asFilename);
    return csvFileFromResult('php://output', $result, $showColumnHeaders);
}

For example:

$result = mysql_query("SELECT foo, bar, shazbot FROM baz WHERE boo = 'foo'");
csvToExcelDownloadFromResult($result);

Check out this question / answer. It's more concise than @Geoff's, and also uses the builtin fputcsv function.

$result = $db_con->query('SELECT * FROM `some_table`');
if (!$result) die('Couldn\'t fetch records');
$num_fields = mysql_num_fields($result);
$headers = array();
for ($i = 0; $i < $num_fields; $i++) {
    $headers[] = mysql_field_name($result , $i);
}
$fp = fopen('php://output', 'w');
if ($fp && $result) {
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="export.csv"');
    header('Pragma: no-cache');
    header('Expires: 0');
    fputcsv($fp, $headers);
    while ($row = $result->fetch_array(MYSQLI_NUM)) {
        fputcsv($fp, array_values($row));
    }
    die;
}

Look at the documentation regarding the SELECT ... INTO OUTFILE syntax.

SELECT a,b,a+b INTO OUTFILE '/tmp/result.txt'
  FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
  LINES TERMINATED BY '\n'
  FROM test_table;

An update to @jrgns (with some slight syntax differences) solution.

$result = mysql_query('SELECT * FROM `some_table`'); 
if (!$result) die('Couldn\'t fetch records'); 
$num_fields = mysql_num_fields($result); 
$headers = array(); 
for ($i = 0; $i < $num_fields; $i++) 
{     
       $headers[] = mysql_field_name($result , $i); 
} 
$fp = fopen('php://output', 'w'); 
if ($fp && $result) 
{     
       header('Content-Type: text/csv');
       header('Content-Disposition: attachment; filename="export.csv"');
       header('Pragma: no-cache');    
       header('Expires: 0');
       fputcsv($fp, $headers); 
       while ($row = mysql_fetch_row($result)) 
       {
          fputcsv($fp, array_values($row)); 
       }
die; 
} 

// Export to CSV
if($_GET['action'] == 'export') {

  $rsSearchResults = mysql_query($sql, $db) or die(mysql_error());

  $out = '';
  $fields = mysql_list_fields('database','table',$db);
  $columns = mysql_num_fields($fields);

  // Put the name of all fields
  for ($i = 0; $i < $columns; $i++) {
    $l=mysql_field_name($fields, $i);
    $out .= '"'.$l.'",';
  }
  $out .="\n";

  // Add all values in the table
  while ($l = mysql_fetch_array($rsSearchResults)) {
    for ($i = 0; $i < $columns; $i++) {
      $out .='"'.$l["$i"].'",';
    }
    $out .="\n";
  }
  // Output to browser with appropriate mime type, you choose ;)
  header("Content-type: text/x-csv");
  //header("Content-type: text/csv");
  //header("Content-type: application/csv");
  header("Content-Disposition: attachment; filename=search_results.csv");
  echo $out;
  exit;
}