problem problem and problem with db

Respected,

i made a database in myphpadmin, through xampp,

databasename: wp_db
dtabaseuser: db_user
password: 123456
db_host: localhost
gave all privileges
and export it to localhost.sql
and upload it,

in wp-config.php file i did the following*

// ** MySQL settings – You can get this info from your web host ** //
/** The name of the database for WordPress */
define(‘DB_NAME’, ‘wp_db’);

/** MySQL database username */
define(‘DB_USER’, ‘wp_user’);

/** MySQL database password */
define(‘DB_PASSWORD’, ‘123456’);

/** MySQL hostname */
define(‘DB_HOST’, ‘localhost’);

it shows me the error
Error establishing a database connection

Please help me what should i do further

Regards
Chimi