PHP MySQL query returning NULL

I have a MySQL table that looks like this:

index  |  tag  |  posts
-------------------------
  1    | cats  |   9,10
  2    | a cat |   9,10
  3    | kitty |   9,10
  4    | meow  |   9,10

I am trying to just return the row that matches a search query. I passed the search parameter using a simple ?search=cats . This is the PHP that I'm using:

$search = $_GET['search'];
$query  = mysql_query("SELECT * FROM tags WHERE tag = '$search'");
echo(mysql_num_rows($query));
$result = mysql_fetch_array($query);
$print  = $result['posts'];
echo($print);

However the mysql_num_rows($query) prints 0 and the $print returns NULL. I can check it with ($print == "") , it evaluates to TRUE and mysql_num_rows($query) returns 4. I tried setting the search query to something that wasn't in the table and it retuned FALSE as expected. I also tried removing the WHERE tag = '$search' and it returns the table like it should.

Is there something I'm overlooking?

Edit

Took everyone's advice and the code I'm using now is:

$search = mysql_real_escape_string($_GET['search']);
var_dump($search); //prints   string(4) "cats"   just like it should
$queryText = "SELECT * FROM tags WHERE tag = '%".$search."%'";
echo($queryText); //SELECT * FROM tags WHERE tag = '%cats%'
$query  = mysql_query($queryText) or die(mysql_error()); //no error
$rows   = mysql_num_rows($query); //this returns 0 and I know it should match 1 row
echo('rows: '.$rows);
$result = mysql_fetch_array($query);
$print  = $result['posts'];
echo($print); //empty

Still have the same problem. The mysql_query is retuning NULL instead of the row or FALSE if it doesn't match.

(in the future I will use the mysqli API, but I would like to finnish this project in mysql . thanks for your suggestions and advice)

---

Ok so after referring to the above edit you made, here is the solution

Use "LIKE" instead of "=" when using wildcard "%"

So your query now should be

$queryText = "SELECT * FROM tags WHERE tag LIKE '%" . $search . "%'";

[I created the exact same db on my local system and ran the same code you gave, After making the above changes, It runs as expected]

---

Try this code now.

Remeber when you want to debug something in PHP the faster way is var_dump not echo. Also you should avoid mysql_api because they are deprecated, use PDO instead PDO on PHP.net

var_dump($_GET); // Just for debuggin if as something

$search = $_GET['search'];
$query  = mysql_query("SELECT * FROM tags WHERE tag = '".mysql_real_escape_string($search)."'");
// echo(mysql_num_rows($query));
$result = mysql_fetch_array($query);
var_dump($result);
//$print  = $result['posts'];
//echo($print);

---

$search = $_GET['search'];
echo $select_query="SELECT * FROM tags WHERE tag = '".mysql_real_escape_string($search)."'";
$query  = mysql_query($select_query);
echo(mysql_num_rows($query));
while($result = mysql_fetch_array($query))
{
  print_r($result);
}

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