Apache – Unable to connect to your database server using the provided settings sql-server 2008

I can’t connect to database. i have these extension php_pdo_sqlsrv_72_ts_x64.dll, php_sqlsrv_72_ts_x64 and added “extension = php_sqlsrv_72….” line in php.ini file. What am i doing wrong?

Unable to connect to your database server using the provided settings.

Filename:
C:/Apache24/htdocs/smartattendanceciwec/system/database/DB_driver.php

Line Number: 436

$active_group = 'default';
$query_builder = TRUE;

$db['default'] = array(
    'dsn'   => '',
    'hostname' => 'localhost',
    'username' => 'sa',
    'password' => 'password',
    'database' => 'Hospital',
    'dbdriver' => 'sqlsrv',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => TRUE,
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE
);