In case it helps, here's 3 different ways of connecting to SQL Server using CodeIgnitor 2 (I am using version 2.2.1) that work for me using Windows 8.1, SQL Server 2012, and PHP 5.3 running under IIS:
In my case I have a named SQL Server instance with name of "MSSQLSERVER2012". If you don't use a named instance you can change (local)\MSSQLSERVER2012 to (local) in all 3 examples below.
Method #1: sqlsrv:
Use these settings in database.php:
$db['local_windows_sqlsrv']['username'] = 'username';
$db['local_windows_sqlsrv']['password'] = 'SQL_PASSWORD_HERE';
$db['local_windows_sqlsrv']['database'] = 'my_db_name';
$db['local_windows_sqlsrv']['hostname'] = '(local)\MSSQLSERVER2012';
$db['local_windows_sqlsrv']['dbdriver'] = 'sqlsrv';
$db['local_windows_sqlsrv']['dbprefix'] = '';
$db['local_windows_sqlsrv']['pconnect'] = FALSE;
$db['local_windows_sqlsrv']['db_debug'] = TRUE;
$db['local_windows_sqlsrv']['cache_on'] = FALSE;
$db['local_windows_sqlsrv']['cachedir'] = '';
$db['local_windows_sqlsrv']['char_set'] = 'utf8';
$db['local_windows_sqlsrv']['dbcollat'] = 'utf8_general_ci';
$db['local_windows_sqlsrv']['swap_pre'] = '';
$db['local_windows_sqlsrv']['autoinit'] = TRUE;
$db['local_windows_sqlsrv']['stricton'] = FALSE;
Method #2: odbc with SQL Server:
First make the change shown here: https://stackoverflow.com/a/9617808/908677
Then use these settings in database.php:
$db['local_windows_odbc']['database'] = 'my_db_name';
$db['local_windows_odbc']['hostname'] = 'Driver={SQL Server};Server=(local)\MSSQLSERVER2012;Database=' . $db['local_windows_odbc']['database'];
$db['local_windows_odbc']['username'] = 'username';
$db['local_windows_odbc']['password'] = 'SQL_PASSWORD_HERE';
$db['local_windows_odbc']['dbdriver'] = 'odbc';
$db['local_windows_odbc']['dbprefix'] = '';
$db['local_windows_odbc']['pconnect'] = FALSE;
$db['local_windows_odbc']['db_debug'] = TRUE;
$db['local_windows_odbc']['cache_on'] = FALSE;
$db['local_windows_odbc']['cachedir'] = '';
$db['local_windows_odbc']['char_set'] = 'utf8';
$db['local_windows_odbc']['dbcollat'] = 'utf8_general_ci';
$db['local_windows_odbc']['swap_pre'] = '';
$db['local_windows_odbc']['autoinit'] = TRUE;
$db['local_windows_odbc']['stricton'] = FALSE;
Method #3: PDO with SQL Server.
UPDATE: This method does work for establishing the connection and inserting rows, but to get querying working you need to upgrade to CodeIgnitor 3.0 as it adds true SQL Server support to PDO.
First make the following change in the __construct() in system/database/drivers/pdo/pdo_driver.php
Replace:
empty($this->database) OR $this->hostname .= ';dbname='.$this->database;
With:
if (strpos($this->hostname, 'sqlsrv') === FALSE)
{
empty($this->database) OR $this->hostname .= ';dbname='.$this->database;
}
Then use these settings in database.php:
// PDO with SQL Server
// IMPORTANT NOTE: requires mod to __construct() in pdo_driver.php to prevent appending ';dbname='.$this->database to hostname
$db['local_windows_pdo']['username'] = 'username';
$db['local_windows_pdo']['password'] = 'SQL_PASSWORD_HERE';
$db['local_windows_pdo']['database'] = 'my_db_name';
$db['local_windows_pdo']['hostname'] = 'sqlsrv:server=(local)\MSSQLSERVER2012;Database=' . $db['local_windows_pdo']['database'];
$db['local_windows_pdo']['dbdriver'] = 'pdo';
$db['local_windows_pdo']['dbprefix'] = '';
$db['local_windows_pdo']['pconnect'] = FALSE;
$db['local_windows_pdo']['db_debug'] = TRUE;
$db['local_windows_pdo']['cache_on'] = FALSE;
$db['local_windows_pdo']['cachedir'] = '';
$db['local_windows_pdo']['char_set'] = 'utf8';
$db['local_windows_pdo']['dbcollat'] = 'utf8_general_ci';
$db['local_windows_pdo']['swap_pre'] = '';
$db['local_windows_pdo']['autoinit'] = TRUE;
$db['local_windows_pdo']['stricton'] = FALSE;