title: The mysql extension is deprecated in Codeigniter 2.2
body: <p>with my Codeigniter 2.2 version and 
  PHP Version 5.5.16-1+deb.sury.org~trusty+1
  and
  Mysql Client API version 5.5.38 
  I get error :</p>
  
  <pre><code>Message: mysql_insert_id(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead
  </code></pre>
  
  <p>But in my  application/config/database.php 'mysqli' is set :</p>
  
  <pre><code>  $db['default']['dbdriver'] = 'mysqli';
    $db['default']['dbprefix'] = 'bp_';
    $db['default']['pconnect'] = TRUE;
    $db['default']['db_debug'] = TRUE;
    $db['default']['cache_on'] = FALSE;
    $db['default']['cachedir'] = '';
    $db['default']['char_set'] = 'utf8';
    $db['default']['dbcollat'] = 'utf8_general_ci';
    $db['default']['swap_pre'] = '';
    $db['default']['autoinit'] = TRUE;
    $db['default']['stricton'] = FALSE;
  </code></pre>
  
  <p>What is wrong ? Which is valid format for pdo and which packet have I to install from my </p>
  
  <pre><code># apt-cache search pdo
  ifupdown - high level tools to configure network interfaces
  php5-mysql - MySQL module for php5
  php5-odbc - ODBC module for php5
  php5-pgsql - PostgreSQL module for php5
  php5-sqlite - SQLite module for php5
  gap-gapdoc - GAPDoc meta package for GAP documentation
  guessnet - Guess which LAN a network device is connected to
  ifupdown-extra - Network scripts for ifupdown
  ifupdown-multi - multiple default gateway support for ifupdown
  ifupdown-scripts-zg2 - Zugschlus' interface scripts for ifupdown's manual method
  irssi-scripts - collection of scripts for irssi
  libjnlp-servlet-java - simple and convenient packaging format for JNLP applications
  mediawiki-extensions-base - Extensions for MediaWiki -- Base package
  netscript-2.4 - Linux 2.4/2.6 router/firewall/VM host network config. system.
  netscript-2.4-upstart - Linux 2.4/2.6 router/firewall/VM host network config. system.
  pd-pdogg - collection of Ogg/Vorbis objects for Pd
  php-apigen - API documentation generator for PHP 5.3+
  php-db - PHP PEAR Database Abstraction Layer
  php-mdb2 - merge of the PEAR DB and Metabase php database abstraction layers
  php-phpdocx - dynamical generation of .docx files
  php-structures-datagrid - Render a data table with automatic pagination and sorting
  php5-mysqlnd - MySQL module for php5 (Native Driver)
  php5-mysqlnd-ms - MySQL replication and load balancing module for PHP
  php5-sybase - Sybase / MS SQL Server module for php5
  python-setupdocs - setuptools plugin that automates building of docs from reST source
  python-sphinxcontrib-httpdomain - Sphinx domain for HTTP APIs
  python-sphinxcontrib.phpdomain - Sphinx "phpdomain" extension
  sheepdog - distributed storage system for QEMU
  </code></pre>