php else statement for empty search

I have a search function which matches keywords from a database and echo's out some html but I'm missing how to enable the handling of empty searches. Can I use an else statement or do I have to redefine the same parameters and use !isset for if not set?

<?php
$con = mysqli_connect("localhost", "database", "password", "table");
if (isset($_GET['search'])) {
    $search_query = $_GET['search_query'];

    global $con;
    $get_item = "select * from database where keywords like '%$search_query%'";
    $run_item = mysqli_query($con, $get_item);
    while ($row_item = mysqli_fetch_array($run_item)) {

        $item_keywords = $row_item['item_keywords'];

        echo "Search found for $item_keywords";
    } // working fine up to here
} else {
    echo "Search not found for $item_keywords";
}
?>