Exportar una tabla mysql a CSV usando código PHP

Tengo una tabla de mi sql llamada pvdata, me gustaría exportarla a un archivo csv.

Pero estoy obteniendo los siguientes resultados en lugar de la tabla de aspecto normal:

 <br />
 <font size='1'><table class='xdebug-error xe-notice' dir='ltr' border='1'cellspacing='0' cellpadding='1'>
 <tr><th align='left' bgcolor='#f57900' colspan="5"><span style='background-color: #cc0000; color: #fce94f; font-size: x-large;'>( ! )</span> Notice: Undefined variable: header in C:\wamp\www\EXPORT TABLE\index.php on line <i>28</i></th></tr>
<tr><th align='left' bgcolor='#e9b96e' colspan='5'>Call Stack</th></tr>
<tr><th align='center' bgcolor='#eeeeec'>#</th><th align='left' bgcolor='#eeeeec'>Time</th><th align='left' bgcolor='#eeeeec'>Memory</th><th align='left' bgcolor='#eeeeec'>Function</th><th align='left' bgcolor='#eeeeec'>Location</th></tr>
<tr><td bgcolor='#eeeeec' align='center'>1</td><td bgcolor='#eeeeec' align='center'>0.0035</td><td bgcolor='#eeeeec' align='right'>256088</td><td bgcolor='#eeeeec'>{main}(  )</td><td title='C:\wamp\www\EXPORT TABLE\index.php' bgcolor='#eeeeec'>..\index.php<b>:</b>0</td></tr>
</table></font>
"id id  state   id  state   Longitude   id  state   Longitude   Latitude    id  state   Longitude   Latitude    Altitude(km)    id  state   Longitude   Latitude    Altitude(km)    Module Tilt id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    Temperature losses coefficient  id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    Temperature losses coefficient  Nominal Operation Cell Temperature  id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    Temperature losses coefficient  Nominal Operation Cell Temperature  Invertor Effeciency id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    Temperature losses coefficient  Nominal Operation Cell Temperature  Invertor Effeciency Persil Name <br />"
<font size='1'><table class='xdebug-error xe-notice' dir='ltr' border='1' cellspacing='0' cellpadding='1'>
<tr><th align='left' bgcolor='#f57900' colspan="5"><span style='background-color: #cc0000; color: #fce94f; font-size: x-large;'>( ! )</span> Notice: Undefined variable: data in C:\wamp\www\EXPORT TABLE\index.php on line <i>49</i></th></tr>
<tr><th align='left' bgcolor='#e9b96e' colspan='5'>Call Stack</th></tr>
<tr><th align='center' bgcolor='#eeeeec'>#</th><th align='left' bgcolor='#eeeeec'>Time</th><th align='left' bgcolor='#eeeeec'>Memory</th><th align='left' bgcolor='#eeeeec'>Function</th><th align='left' bgcolor='#eeeeec'>Location</th></tr>
<tr><td bgcolor='#eeeeec' align='center'>1</td><td bgcolor='#eeeeec' align='center'>0.0035</td><td bgcolor='#eeeeec' align='right'>256088</td><td bgcolor='#eeeeec'>{main}(  )</td><td title='C:\wamp\www\EXPORT TABLE\index.php' bgcolor='#eeeeec'>..\index.php<b>:</b>0</td></tr>
</table></font>"id  state   Longitude   Latitude    Altitude(km)    Module Tilt Module Azimuth  Rated Peak Power(kW)    Temperature losses coefficient  Nominal Operation Cell Temperature  Invertor Effeciency Persil Name "
"1  ""persil""  ""0""   ""0""   ""0""   ""0""   ""0""   ""0""   ""0.0047""  ""47""  ""0.9"" ""PERSIL07"""
"2  ""other""   ""12""  ""12""  ""0""   ""15""  ""150"" ""12""  ""0.0046""  ""45""  ""0.95""    ""predefined"""

Mi código php es:

  <?php

$username = "root";
$password = "";
$hostname = "localhost"; 

$dbhandle = mysql_connect($hostname, $username, $password) 
  or die("Unable to connect to MySQL");

$selected = mysql_select_db("user data smart grid",$dbhandle) 
  or die("Could not select Data Base");

    header("Content-type: application/csv");
    header("Content-Disposition: attachment; filename=pvdata.csv");
    header("Pragma: no-cache");
    header("Expires: 0");



$query = "SELECT * FROM pvdata";

$export = mysql_query ($query ) or die ( "Sql error : " . mysql_error( ) );

$fields = mysql_num_fields ( $export );

for ( $i = 0; $i < $fields; $i++ )
{
    $header .= mysql_field_name( $export , $i ) . "\t";

    echo $header;
}

while( $row = mysql_fetch_row( $export ) )
{
    $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 );

if ( $data == "" )
{
    $data = "\n(0) Records Found!\n";                        
}

print "$header\n$data";

exit();

?>

Entonces, ¿qué está mal? Si exporto la tabla manualmente desde el phpmyadmin, funciona bien. También quiero obtener los nombres de las columnas en la tabla si es posible.

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