由于错误是由调用 mysql_real_escape_string() 引发的，这意味着您没有调用 mysql_connect() 首先将有效的数据库句柄传递给 mysql_real_escape_string(或对 mysql_connect() 的调用失败).

Since the error is being thrown by the call to mysql_real_escape_string() it rather implies that you didn't call mysql_connect() first and pass a valid db handle to mysql_real_escape_string (or the call to mysql_connect() failed).

在某些情况下，mysql 扩展将尝试使用 php.ini 中的默认设置自动连接，如果这些不可用，则故障转移到 my.cnf - 这显然是无效的.或者可能是设置有效但mysqld没有运行.

In some circumstances, the mysql extension will attempt to connect automatically using the default settings in php.ini, failing over to my.cnf if these are not available - which obviously are not valid. Or it may be that the settings are valid but the mysqld is not running.

你有成功连接到数据库的脚本吗?

Have you got scripts which are connecting to the database successfully?

你有数据库的用户名和密码吗?

Do you have a username and password for the database?

试试:

check_running();

$user=''; // fill in your details
$password=''; // fill in your details

$hosts=array(
  'localhost', '127.0.0.1', $_SERVER['HTTP_HOST'], $_SERVER['SERVER_ADDR']
);
foreach ($hosts as $addr) {
   try_con($addr, $user, $password);
   try_con($addr . ':3306', $user, $password);
}

function try_con($host, $user, $password)
{
 $dbh=mysql_connect($host, $user, $password);
 if ($dbh) {
     print "Connected OK with $host, $user, $password<br />
";
 } else {
     print "Failed with $host, $user, $password<br />
";
 }
}

function check_running()
{
   // this assumes that you are using Apache on a Unix/Linux box
   $chk=`ps -ef | grep httpd | grep -v grep`;
   if ($chk) {
      print "Checking for mysqld process: " . `ps -ef | grep mysqld | grep -v grep` . "<br />
";
   } else {
       print "Cannot check mysqld process<br />
";
   }
 }