Try / catch in mysqli

Question

I'm following an OOP mysqli course. When connecting to the database, they use the following script:

$db = new mysqli("host", "user", "password", "database");
if ($db->connect_error){
    $error = $db->connect_error;
    echo("Not connected: " . $error);
}

Later though, they call the database connection file with a try / catch block:

try {
    require_once "connection.php";
}catch (Exception $e){
    $error = $e->getMessage();
    echo $error;
}

Isn't a possible connection error being handled by the connection file immediately after trying to connect? Is the try / catch block basically doing the same thing? Or is the try / catch block looking for a different type of error?

UPDATE: Just to clarify, after reading some of the answers. When I just do this:

try {
    $db = new mysqli("host", "user", "password", "database");
}catch (Exception $e){
    $error = $e->getMessage();
    echo $error;
}

assuming that the database access data is wrong (for example a wrong host), I get a PHP warning but not the error output in the catch block. Shouldn't the catch detect this error?

Answer 1

If you need to catch exceptions on mysqli extension by use try/catch block, try this code (switch on exception mode instead of classic error reporting):

// Method 1:
$driver = new mysqli_driver();
$driver->report_mode = MYSQLI_REPORT_STRICT | MYSQLI_REPORT_ERROR;

// OR Method 2:
mysqli_report(MYSQLI_REPORT_STRICT | MYSQLI_REPORT_ALL);

try {
    $db = new mysqli("host", "user", "password", "database");
} catch (mysqli_sql_exception $e) {
    ...
}

mysqli_sql_exception mysqli_driver