mysqli_error() expects exactly 1 argument

The error message "mysqli_error() expects exactly 1 argument" indicates that the mysqli_error() function requires one argument to be passed into it, but none or more than one arguments were provided.

The mysqli_error() function is used to retrieve the last error message generated by the most recent mysqli function call. To use this function, you need to pass the mysqli object as the only argument. For example:

$conn = mysqli_connect("localhost", "username", "password", "dbname");

// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// Perform a query
$sql = "SELECT * FROM users";
$result = mysqli_query($conn, $sql);

// Check for errors
if (!$result) {
    echo "Error: " . mysqli_error($conn);
}

// Close connection
mysqli_close($conn);

In this example, the mysqli_error() function is used to retrieve any error messages generated by the mysqli_query() function. The mysqli object ($conn) is passed as the argument to the function.