PHP搜索引擎不工作？

Question

I'm working on a simple search engine that gets you information but I'm having a problem. You see when I put a space into the search input it doesn't give you the message saying "no key words searched please try again" but when you click the search button without adding anything in the search input it works. How could i fix this to make it work with both?

Code:

if(!$db) {
    die('sorry we are having some problbems');
}


$searchTerm = mysqli_real_escape_string($db,$_GET['term']);

if ( empty($searchTerm))
{
echo("no key words searched please try again");
}
else
{
$sql = mysqli_query(
    $db,
    sprintf(
        "SELECT * FROM searchengine WHERE name LIKE '%s' LIMIT 0,20",
        '%'. $searchTerm .'%'
    )
);

while($ser = mysqli_fetch_array($sql)) {
    echo "<a href='$ser[pageurl]'>$ser[img]</a>";
}
}

mysqli_close($db);
?>

Answer 1

Check for whitespace in addition to the empty search term. Here I'm using the regular expressions preg_match to find any whitespace characters that could be entered.

if (empty($searchTerm)||preg_match('!^\s+$!',$searchTerm))
  {
    echo("no key words searched please try again");
  }
else...

Or with preg_match alone

if (preg_match('!^\s*$!',$searchTerm))
  {
    echo("no key words searched please try again");
  }
else...

Another method you could use is to check the string length using strlen

if (strlen($searchTerm)<4)
  {
    echo("no key words searched please try again");
  }
else...