php实现mysql数据库分表分段备份

<?php
//宋正河 网络推广网站推广转载请注明出处
set_time_limit(0);
header('content-type:text/html;charset=utf-8');
mysql_connect('localhost','root','root');
mysql_select_db('test');
$table_array=get_tables('test');
mysql_query('set names utf8');
$filesize=102410244;
$start=$_GET['start']?$_GET['start']:0;
$part=$_GET['part']?$_GET['part']:'1';
$table_index=$_GET['table_index']?$_GET['table_index']:'0';
$table=$table_array[$table_index];
$num=200000000;//这个数要足够大,可以是总记录数
$backupdata='';
if($start=='0'){
$query="SHOW CREATE TABLE `{$table}`";
$result = mysql_query($query);
$row = mysql_fetch_row($result);
$backupdata .= "DROP TABLE IF EXISTS `{$table}`;\n" . $row[1] . ";\n\n";
}
$limit=($start=='0')?'':" limit $start,$num ";
$query="select  from `{$table}` $limit ";
$result=mysql_query($query);
$numfields = mysql_num_fields($result); //统计字段数
while($row=mysql_fetch_row($result)){
$ma = ''; //存储逗号
$backupdata_tmp = "INSERT INTO `{$table}` VALUES (";
for($i=0; $i<$numfields; $i++){
$backupdata_tmp .= $ma . "'" . mysql_escape_string($row[$i]) . "'";
$ma = ',';
}
$backupdata_tmp .= ");\n";
if(strlen($backupdata)+strlen($backupdata_tmp) > $filesize){
//写入文件并跳转
$file='data/'.$table.'-'.$part.'.sql';
file_put_contents($file,$backupdata);
echo $file.' 备份完成，程序继续进行！';
$part++;
//分段
//表名
//起点
//跳转
sleep(3);
echo "<script>location.href='?start={$start}&table_index={$table_index}&part={$part}';</script>";
exit;
}
$backupdata.=$backupdata_tmp;
$start++;
}
if($backupdata){
$file='data/'.$table.'-'.$part.'.sql';
file_put_contents($file,$backupdata);
}
echo $table.'备份完成！<br />';
sleep(2);
$table_index++;
if($table_array[$table_index]){
echo "<script>location.href='?table_index={$table_index}';</script>";
exit;
}else{
echo '恭喜你，数据库备份完毕！';
}
function get_tables($db){
$tq = mysql_list_tables($db);
while($tr = mysql_fetch_row($tq)){
$arrtb[] = $tr[0];
}
return $arrtb;
}
?>