I am a newbie to PHP and need help in exporting a selected content from Mysql Table to MS Excel using PHP. I need this done by a click of a button or a link.
Below is a piece of code I have done so far but I am consistently getting a warning as "Cannot modify header information - headers already sent". Also suggest a good way to export table on a click of a button\link. Thanks
//Export Contents
$header = '';
$data = '';
$fields = mysql_num_fields($sql);
//fetch header
for($i=0; $i < $fields; $i++)
{
    $header .= mysql_field_name($sql, $i)."\t";
}
//fetch data each row, store on tabular row data
while($row = mysql_fetch_row($sql))
{
    $line = '';
    foreach($row as $value)
    {
        if(!isset($value) || $value == "")
        {
            $value = "\t";
        }
        else
        {
            $value = str_replace('"', '""', $value);
            $value = '"'.$value.'"'."\t";
        }
        $line .= $value;
    }
    $data .= trim($line)."\n";
    $data = str_replace("\r", "", $data);
}
//Naming the excel sheet
$name = $customerFilter."_".date('d-m-y').".xls";
header("Content-type:application/vnd.ms-excel;name='excel'");
header("Content-Disposition: attachment; filename=$name");
header("Pragma: no-cache");
header("Expires: 0");
//Output Data
echo $header."\n\n".$data;
 
     
     
     
    