To use mysqli or PDO?

I’m trying to make my mind up about whether I should be using mysqli or PDO for a project I’m just starting and I’ve found a few relevant articles:

And based on all of that I think I’ve decided to use PDO.

MySQL: Error in SQL: Commands out of sync; you can’t run this command now

Today I was programming MySQL via PHP and I received an error “Error in SQL: Commands out of sync; you can’t run this command now”. It turned out the problem was that a previous mulit_query had mysqli_results that hadn’t been freed. This article helped me solve the problem, and now my batch mode SQL processor looks like this:

  public function execute_batch( $sql ) {


    if ( ! $this->link->multi_query( $sql ) ) {

      $this->throw_error( $sql );


    if ( $this->link->more_results() ) {

      do {
        $result = $this->link->use_result();
        if ( $result instanceof mysqli_result ) {
      while ( $this->link->more_results() && $this->link->next_result() );


This code executes the SQL batch and then frees any mysqli_results that result from the query batch.

MySQL SSL connections not working with phpMyAdmin and mysqli

I had a problem with phpMyAdmin not using encrypted connections.

My server was correctly configured for SSL as indicated by:


Which returned:

Variable_name Value
have_openssl YES
have_ssl YES
ssl_ca /etc/mysql/cacert.pem
ssl_cert /etc/mysql/server-cert.pem
ssl_key /etc/mysql/server-key.pem

However when I ran:


I got back a null result, indicating that the connection was not encrypted.

Eventually I figured out that the problem was caused by using the ‘mysqli’ provider for my connections in phpMyAdmin. When I switched my connections to use ‘mysql’ instead then encryption started working and an Ssl_cipher was reported.

I’d love to know what the actual problem is, but for now I’m just happy that my connections are actually encrypted. I spent a while hacking on the mysqli dbi interface to try and get it to play nice with SSL but I didn’t make any progress.