使用 PHP 代码将 mysql 表导出为 CSV

我有一个名为 pvdata 的 sql 表，我想将其导出到 csv 文件。

但我得到以下结果而不是正常的表格：

 <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"""

我的 PHP 代码是：

  <?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();

?>

那么出了什么问题呢？ 如果我从 phpmyadmin 手动导出表，它工作正常。 如果可能的话，我还想获取表中列的名称。

在 for 循环之前将 $header 初始化为空字符串。

$header = '';//initialize header
for ( $i = 0; $i < $fields; $i++ )
{
    $header .= mysql_field_name( $export , $i ) . "\t";

    echo $header;//remove this line
}

EDIT

还在 while 循环之外初始化 $data。

$data = '';
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";
}