php - mysqli_select_db() expects parameter 1 to be mysqli, string given

Question

I am new to Mysqli_* and I am getting these errors:

Warning: mysqli_select_db() expects parameter 1 to be mysqli, string given in D:Hosting9864230htmlincludesconnection.php on line 11

Warning: mysqli_error() expects exactly 1 parameter, 0 given in D:Hosting9864230htmlincludesconnection.php on line 13

Database selection failed:

<?php
require("constants.php");

// 1. Create a database connection
$connection = mysqli_connect(DB_SERVER,DB_USER,DB_PASS);
if (!$connection) {
    die("Database connection failed: " . mysqli_error());
}

// 2. Select a database to use 
$db_select = mysqli_select_db(DB_NAME,$connection);
if (!$db_select) {
    die("Database selection failed: " . mysqli_error());
}
?>

Answer 1

Your arguments are in the wrong order. The connection comes first according to the docs

<?php
require("constants.php");

// 1. Create a database connection
$connection = mysqli_connect(DB_SERVER,DB_USER,DB_PASS);

if (!$connection) {
    error_log("Failed to connect to MySQL: " . mysqli_error($connection));
    die('Internal server error');
}

// 2. Select a database to use 
$db_select = mysqli_select_db($connection, DB_NAME);
if (!$db_select) {
    error_log("Database selection failed: " . mysqli_error($connection));
    die('Internal server error');
}

?>