Question

From some application, I can’t connect to a remote database server:

  MYSQL conn;  

  if(!mysql_init(&conn))
      std::wcout << "Error: can't create MySQL-descriptor" << endl;   

  if(!mysql_real_connect(&conn,"ip","user","password","dbname",0,0,0))
       std::wcout << "Error: can't connect to MySQL server" << endl;     

  if(mysql_query(&conn, "SELECT VERSION()") != 0)
       std::wcout << "Error: can't execute SQL-query" << endl;

I opened port 3306 on the remote server:

 iptables -A INPUT -p tcp -m tcp --dport 3306 -j ACCEPT 
 iptables save
 iptables restart

Error:

Failed to connect to database:Error: Can’t connect to MySQL server on
‘ip_..’ (10060)

What could be the reason?

Answer 1

You should display result of mysql_error after every failed test (following a successful mysql_init), e.g.:

 if(!mysql_real_connect(&conn,"ip","user","password","dbname",0,0,0))
     std::wcout << "Error: can't connect to MySQL server:"
                << mysql_error (&conn) << endl; 

otherwise your user won’t be able to understand what is happening to him.

You’ll probably find out what is happening. If not, look into the documentation.