Fatal error: Call to undefined function: mssql_connect() in

<?php

ini_set('max_execution_time', 600);
ini_set("memory_limit","1024M");

//----------------Parametres de connexion à la base de données--------------------------//
$servername='';
$database_username='';
$database_password='';
$database_name='';

//----------------Parametres de connexion Solsys--------------------------//
$host = ""; 
$user = "";
$mdpbdd  = "";
$[/contents/104-bases-de-donnees-introduction bdd] = "l";

    


mysql_connect($servername,$database_username,$database_password);
mysql_select_db($database_name);
	
mssql_connect($host, $user,$mdpbdd) or die("Erreur de connexion au serveur");
mssql_select_db($bdd) or die("Erreur de connexion a la base de donnees");
	
	
	
//$batch = "SELECT products_id, upc, stock FROM declinaison_stock_produit where upc <> '' order by products_id desc";
$batch = "SELECT id_product, id_product_attribute, upc, quantity FROM ps_product_attribute where upc = '56940'";
$requete = mysql_query($batch);
$[/contents/498-html-langage html] = '';
while ($resultat = mysql_fetch_array($requete))
	{
    
		if ($resultat['upc'] != '')
		{
			$idArt = $resultat['upc'];
			
			$query = mssql_query('SELECT IdArt, quantite FROM dbo.StockMag WHERE IdArt='.$idArt);
	    		
			$a = array();
			for($i=0;$i<mssql_num_rows($query);$i++)
			{
				$a[] = mssql_result($query, $i, 'quantite');
			}
			$som = Array_sum($a);
            //print_r($a);die;
			
			$html .= '<p>'.$resultat['upc'].' dans base de = '.$resultat['stock'];
			$html .= "<br /><b>TOTAL Stock code article dans central $som</b></p>";
			
			if ($resultat["stock"] != $som ) 
				{
                    $delay_msg_sql = '';
                    if( $som > 0 )
                        $delay_msg_sql = ', etat_dispo = 1';
                    else
                        $delay_msg_sql = ', etat_dispo = 4, etat_dispo_externe = "Livraison sous 10 a 15 jours"';
                
                    
		mysql_query("UPDATE declinaison_stock_produit set stock=$som $delay_msg_sql WHERE upc=$idArt");  
				
				} 
		}
	}
	
	mysql_close;
	echo '<br /><h1>fin du batch</h1>';