This is my php code. How to check if this 3 parameters (user,agwera,vis) exist in MySQL with PHP? And if already exist don't add a second time. + want `echo "Already in Exists<br/>";`

```
    <?
sleep(10);
define ('DBHOST', 'yyy');
define ('DBNAME', 'xxxx');
define ('DBUSER', 'xxxx');
define ('DBPASS', 'xxxxx');

mysql_pconnect(DBHOST, DBUSER, DBPASS) or die('DB');
mysql_select_db(DBNAME) or die ('USER');
mysql_query('SET NAMES utf8');

header('Content-Type: text/html; charset=utf-8');
error_reporting (0);
$act = isset($_GET['act']) ? $_GET['act'] : '';
switch($act)
{
case 'send':
$destination = $_POST['adress']; 
$signature = $_POST['text']; 
$text = "$signature ";

if (empty($_POST["text"])  or strlen($_POST["text"])==0){

@header("location:error5.php");
break;

}

$str = $_POST['text']; 
if (strlen($str)>160){
@header("location:error4.php");
break;

}

if (!preg_match('/^[0-9]{9}$/',$destination))
{
@header("location:error1.php");
break;
}

$str2 = $_POST['sender'];
if (strlen($str2)>11){
@header("location:error2.php");
break;
}

if (empty($_POST["sender"])  or strlen($_POST["sender"])==0){

@header("location:error3.php");
break;

}

else
{

    $password = 'zzzzzz';
    $destination = $_POST['adress']; 
  $nomeri = "995$destination";
    $nomeri2 = $_POST['sender']; 
    $source = $nomeri2;
    $signature = $_POST['text']; 
    $text = "$signature "; 

    $content = 
                'key='.rawurlencode($password). 
                '&destination='.rawurlencode($nomeri). 
                '&sender='.rawurlencode($source). 
                '&content='.rawurlencode($text); 

    $a = file_get_contents('http://example.com/api/send.aspx?'.$content); 

@header("location:ok.php");

mysql_query("INSERT `gagzavnili` SET
                      `user`        =   '".$source."',
                      `agwera`      =   '".$text."',
                      `vis`     =   '".$destination."',
                      `time_upload` =   '".time()."',
                      `time`        =   '".time()."'") or die(mysql_error());
                       $file_id = mysql_insert_id();

}
}
?>

```