$sql_tbl_clients = " SELECT  num1, 
                               
                 
                        FROM clients
        
                           WHERE num1      ='1'  "; 

$sql_tbl_clients = " SELECT  num1
                 
                        FROM clients
        
                           WHERE num1      ='$num1'


$sql_resulclients = mysql_query( $sql_tbl_clients ); 
   if ( mysql_error() != '' ) {
      $message = mysql_error(); 
      header("Location: $error_page?code=$error_mysql_query&message=$message");
      exit;
   }

   $rowclients = mysql_fetch_array( $sql_resulclients );
   if ( mysql_error() != '' ) {
      $message = mysql_error(); 
      header("Location: $error_page?code=$error_mysql_query&message=$message");
      exit;
   }

"; 

//Construction de la requete
$requete = "SELECT COUNT(*) FROM maTable WHERE err_no =".$num;
//Exécution de la requete
$o_result = mysql_query($requete);

//Récupération du résultat
$nb_result = mysql_fetch_result($o_result, 0, 0)

//Si aucun résultat
if ($nb_result == 0)
  echo "Aucun client";

$requete = "SELECT COUNT(*) FROM clients WHERE err_no = $num1 "; 
//Exécution de la requete 
$o_result = mysql_query($requete); 

//Récupération du résultat 
$nb_result = mysql_fetch_result($o_result, 0, 0) 

//Si aucun résultat 
if ($nb_result == 0) 
  echo "Aucun client"; 

//Si aucun résultat
if ($nb_result == 0){
  echo "Aucun client";
}
else {
//sinon
}

$var = ($test == 0) ? "coucou" : "rien";

if ($test == 0)
  $var = "coucou";
else
  $var = "rien";

$requete = "SELECT COUNT(*) FROM clients WHERE err_no = ".$num1;

2  $requete = "SELECT COUNT(*) FROM clients WHERE err_no = ".$num1;
3  //Exécution de la requete 
4  $o_result = mysql_query($requete); 
5
6  //Récupération du résultat 
7  $nb_result = mysql_fetch_result($o_result, 0, 0) 
8
9  //Si aucun résultat 
10  if ($nb_result == 0){ 
11  echo "Aucun client"; 
12  } 
13  else { 
14  //sinon 
15 } 

$nb_result = mysql_result($o_result, 0, 0);