<?php   
/*程序功能：mysql数据库备份功能*/
ini_set('max_execution_time','0');
ini_set('memory_limit','1024M');//加上这两行,可以备份大数据,昨晚测了一下公司的一个600M的表,很快就可以备份成功
$code_type = 'gbk';
header("Content-type:text/html;charset=$code_type");
header("Content-disposition:   filename=backup.sql");//所保存的文件名   
header("Content-type:   application/octetstream");   
header("Pragma:   no-cache");   
header("Expires:   0");   
$conn   =   mysql_connect("localhost","root","root");   
$db   =   mysql_select_db($dbname,$conn);   
mysql_query("set names $code_type");
$dbname="test";//数据库名
$flag  = '1';//1:全部备份,2:只备份表结构,3:只备份数据
echo back_database($dbname,$conn,$flag);//备份数据库



//开始备份
function back_database($dbname,$conn,$flag='1'){
$crlf="\r\n";
$str = '';
$now = date('Y年m月d日H点i分s秒',time());
$str .=   "$crlf--$crlf-- 数据库: `$dbname`$crlf--$crlf-- 导出日期: `$now`$crlf--$crlf";
$str .=   "$crlf--$crlf-- 作者: ****$crlf--$crlf-- QQ: 1019822077$crlf--$crlf";
$str .=   "-- blog: http://hi.baidu.com/woaidelphi/blog$crlf--$crlf";
$str .=   "SET SQL_MODE=\"NO_AUTO_VALUE_ON_ZERO\";$crlf";
$tables       =   mysql_list_tables($dbname,$conn);   
$num_tables   =   mysql_numrows($tables);//表的总数 
$i   =   0;
while($i<$num_tables){//循环所有的表     
$table =   mysql_tablename($tables,$i);   
//备份表结构
if($flag=='1' or $flag=='2'){
$query =   mysql_query("SHOW CREATE TABLE $table");
$row   =   mysql_fetch_row($query);
$str .=  "-- --------------------------------------------------------$crlf$crlf";
$str .=  "--$crlf-- 表的结构 `$table` $crlf--$crlf";
$str .=  $row[1].";$crlf--$crlf";
}
//备份表内容 
if($flag=='1' or $flag=='3'){
$str .= "--$crlf-- 导出表中的数据 `$table` $crlf--$crlf";
$str .=  get_table_content($dbname,$table);
$str .= "$crlf$crlf";
}
$i++;   
}
return $str;
}
//得到表中的记录sql   
function   get_table_content($dbname,$table){   
$crlf            =   "\r\n";
$schema_create   =   "";   
$temp            =   "";   
$result          =   mysql_db_query($dbname,"SELECT   *   FROM   $table");   
$i               =   0;   
while($row   =   mysql_fetch_row($result)){   
$schema_insert   =   "INSERT   INTO   $table   VALUES   (";   
for($j=0;   $j<mysql_num_fields($result);$j++){   
if(!isset($row[$j]))   
$schema_insert   .=   "   NULL,";   
elseif($row[$j]   !=   "")   
$schema_insert   .=   "   '".addslashes($row[$j])."',";   
else   
$schema_insert   .=   "   '',";   
}   
$schema_insert   =   ereg_replace(",$",   "",   $schema_insert);   
$schema_insert   .=   ");$crlf";   
$temp   =   $temp.$schema_insert   ;   
$i++;   
}   
return   $temp;   
}