// 备份数据库  $host = "localhost";  $user = "root"; //数据库账号  $password = ""; //数据库密码  $dbname = "mysql"; //数据库名称  // 这里的账号、密码、名称都是从页面传过来的  if (!mysql_connect($host, $user, $password)) // 连接mysql数据库  {  echo '数据库连接失败，请核对后再试';  exit;  }  if (!mysql_select_db($dbname)) // 是否存在该数据库  {  echo '不存在数据库:' . $dbname . ',请核对后再试';  exit;  }  mysql_query("set names 'utf8'");  $mysql = "set charset utf8;\r\n";  $q1 = mysql_query("show tables");  while ($t = mysql_fetch_array($q1))  {  $table = $t[0];  $q2 = mysql_query("show create table `$table`");  $sql = mysql_fetch_array($q2);  $mysql .= $sql['Create Table'] . ";\r\n";  $q3 = mysql_query("select * from `$table`");  while ($data = mysql_fetch_assoc($q3))  {  $keys = array_keys($data);  $keys = array_map('addslashes', $keys);  $keys = join('`,`', $keys);  $keys = "`" . $keys . "`";  $vals = array_values($data);  $vals = array_map('addslashes', $vals);  $vals = join("','", $vals);  $vals = "'" . $vals . "'";  $mysql .= "insert into `$table`($keys) values($vals);\r\n";  }  }  $filename = $dbname . date('Ymjgi') . ".sql"; //存放路径，默认存放到项目最外层  $fp = fopen($filename, 'w');  fputs($fp, $mysql);  fclose($fp);  echo "数据备份成功";  ?>