将两张桌子放在一起时，如何才能使照片只能搜索？

I've brought two tables together from one database which has a search function applied. At the moment 'photos' are being narrowed down when searching but the contents from 'sponsor' is always displayed. Ideally I want everything to be displayed before searching but then on a search 'sponsor' results will never appear. I've tried to put the $search in the first half with 'photos' but that does the above action. What can I add to stop this?

SELECT * FROM photos 
WHERE title LIKE '%".$search."%'
UNION SELECT * FROM sponsor
ORDER BY id DESC

You could use two different SQL statements depending on whether or not $search is present.

if ($search) {
    $sql = "SELECT * FROM photos
            WHERE title LIKE '%".$search."%'
            ORDER BY id DESC";
} else {
    $sql = 'SELECT * FROM photos
            UNION SELECT * FROM sponsor
            ORDER BY id DESC';
}