diff --git a/build/api/core/Request.php b/build/api/core/Request.php
index dce1f28..f9a9ac3 100755
--- a/build/api/core/Request.php
+++ b/build/api/core/Request.php
@@ -5,7 +5,8 @@
 	use \api\core\AuthSystem;
 	use \api\core\ModuleFactory;
 	use \api\core\Config;
-	use \error\core\Error;
+use database\core\Repo;
+use \error\core\Error;
 	use \error\core\Err;
 
 
@@ -503,6 +504,11 @@
 			/* (3) On ajoute les données */
 			$response->appendAll($returned);
 
+			/* (4) Si le Debug est actif on ajoute le debug des repo */
+			if(Repo::isDebugEnabled()){
+				$response->append("repoDebug" , Repo::getDebug());
+			}
+
 			/* (4) On retourne la réponse */
 			return $response;
 
diff --git a/build/api/module/excelController.php b/build/api/module/excelController.php
index e3c4a4d..2e1fb4b 100644
--- a/build/api/module/excelController.php
+++ b/build/api/module/excelController.php
@@ -63,9 +63,11 @@ class excelController
 				$addEU = function() use (&$UECode,&$allUE,&$UE){
 					//determine if UE is disabled (if cours+td+tp = 0)
 					$totalVH = 0;
-					foreach ($UE["groups"] as $groups){
-						foreach ($groups as $group){
-							$totalVH += $group["VH"];
+					if(is_array($UE["groups"]) && count($UE["groups"]) > 0){
+						foreach ($UE["groups"] as $groups){
+							foreach ($groups as $group){
+								$totalVH += $group["VH"];
+							}
 						}
 					}
 
@@ -348,6 +350,10 @@ class excelController
 				/** @var tp $tpRepo */
 				$tpRepo = Repo::getRepo("tp");
 
+				$CoursToLink = [];
+				$TDToLink = [];
+				$TPToLink = [];
+
 				foreach ($allUE as $codeUE => $UE){
 
 					if($UE["defaultFormation"]){
@@ -377,22 +383,25 @@ class excelController
 
 								switch ($type){
 									case "Course":
-										$coursRepo->create(	$codeUE,
-															$allProf[$group["professor"]]["dbId"],
-													$UE["disabled"] ? $UE["CourseVH"] : $group["VH"],
-															$formations);
+										$CoursToLink[] = ["id" => $coursRepo->create(	$codeUE,
+																					$allProf[$group["professor"]]["dbId"],
+																			$UE["disabled"] ? $UE["CourseVH"] : $group["VH"],
+																					[]),
+														"form" => $formations];
 										break;
 									case "TD":
-										$tdRepo->create($codeUE,
-														$allProf[$group["professor"]]["dbId"],
-												$UE["disabled"] ? $UE["TdVH"] : $group["VH"],
-														$formations);
+										$TDToLink[] = ["id" => $tdRepo->create($codeUE,
+																					$allProf[$group["professor"]]["dbId"],
+																			$UE["disabled"] ? $UE["TdVH"] : $group["VH"],
+																					[]),
+														"form" => $formations];
 										break;
 									case "TP":
-										$tpRepo->create($codeUE,
-														$allProf[$group["professor"]]["dbId"],
-												$UE["disabled"] ? $UE["TpVH"] : $group["VH"],
-														$formations);
+										$TPToLink[] = ["id" => $tpRepo->create($codeUE,
+																				$allProf[$group["professor"]]["dbId"],
+																		$UE["disabled"] ? $UE["TpVH"] : $group["VH"],
+																				[]),
+														"form" => $formations];
 										break;
 								}
 
@@ -401,7 +410,28 @@ class excelController
 					}
 				}
 
-				return [ 'data' => ["professors" => $allProf, "formations" => $allFormations, "UEs" => $allUE ] ];
+				Repo::enableStacking();
+
+				foreach ($CoursToLink as $cour){
+					foreach ($cour["form"] as $formation){
+						$coursRepo->linkFormation($formation,$cour["id"]);
+					}
+				}
+				foreach ($TDToLink as $cour){
+					foreach ($cour["form"] as $formation){
+						$tdRepo->linkFormation($formation,$cour["id"]);
+					}
+				}
+				foreach ($TPToLink as $cour){
+					foreach ($cour["form"] as $formation){
+						$tpRepo->linkFormation($formation,$cour["id"]);
+					}
+				}
+
+				Repo::flushStack();
+
+				//return [ 'data' => ["professors" => $allProf, "formations" => $allFormations, "UEs" => $allUE ] ];
+				return["data" => true];
 			}catch (Exception $e){
 				return [ 'error' => new Error(Err::UnknownError) ];
 			}
diff --git a/build/database/core/DatabaseDriver.php b/build/database/core/DatabaseDriver.php
index a7553fd..695b06d 100755
--- a/build/database/core/DatabaseDriver.php
+++ b/build/database/core/DatabaseDriver.php
@@ -11,6 +11,7 @@
 	**************************/
 
 	namespace database\core;
+	use database\core\PDOWrapper\PDOWrapper;
 	use \error\core\Error;
 	use \error\core\Err;
 
@@ -60,7 +61,7 @@
 		* @password<String> 									Database password
 		*
 		*/
-		private function __construct($host, $dbname, $username, $password){
+		private function __construct($host, $dbname, $username, $password, $debug = false){
 			/* (2) Stores configuration */
 			$this->host     = $host;
 			$this->dbname   = $dbname;
@@ -69,14 +70,19 @@
 
 			try{
 
-				$this->pdo = new \PDO('mysql:host='.$this->host.';dbname='.$this->dbname.';charset=utf8', $this->username, $this->password, [
+				$this->pdo = new PDOWrapper('mysql:host='.$this->host.';dbname='.$this->dbname.';charset=utf8', $this->username, $this->password, [
 					\PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
-					\PDO::ATTR_TIMEOUT            => 5
+					\PDO::ATTR_TIMEOUT            => 5,
+					\PDO::ERRMODE_EXCEPTION		  => true
 				]);
 
 				$this->pdo->setAttribute(\PDO::ATTR_STRINGIFY_FETCHES, false);
 				$this->pdo->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
 
+				if($debug){
+					$this->pdo->enableDebug();
+				}
+
 				// On signale que tout s'est bien passe
 				$this->error = new Error(Err::Success);
 
@@ -118,7 +124,7 @@
 
 				/* (1) If local -> instanciates with local configuration */
 				// if( !checkdnsrr($_SERVER['SERVER_NAME'], 'NS') )
-					self::$instance[$label] = new DatabaseDriver($conf[$label]['local']['host'], $conf[$label]['local']['dbname'], $conf[$label]['local']['user'], $conf[$label]['local']['password']);
+					self::$instance[$label] = new DatabaseDriver($conf[$label]['local']['host'], $conf[$label]['local']['dbname'], $conf[$label]['local']['user'], $conf[$label]['local']['password'],$conf[$label]['local']['debug']);
 				/* (2) If Remote -> instanciates with Remote configuration */
 				// else
 				// 	self::$instance[$label] = new DatabaseDriver($conf[$label]['remote']['host'], $conf[$label]['remote']['dbname'], $conf[$label]['remote']['user'], $conf[$label]['remote']['password']);
@@ -194,6 +200,22 @@
 			];
 		}
 
+		public function enableStacking(){
+			$this->pdo->enableStacking();
+		}
+
+		public function flushStack(){
+			$this->pdo->executeStack();
+		}
+
+		public function getDebug() : array{
+			return $this->pdo->getDebug();
+		}
+
+		public function isDebugEnabled() : bool {
+			return $this->pdo->isDebugEnabled();
+		}
+
 
 
 	}
diff --git a/build/database/core/PDOWrapper/PDOStatementWrapper.php b/build/database/core/PDOWrapper/PDOStatementWrapper.php
new file mode 100644
index 0000000..704d5bb
--- /dev/null
+++ b/build/database/core/PDOWrapper/PDOStatementWrapper.php
@@ -0,0 +1,51 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: lucas
+ * Date: 30/08/16
+ * Time: 17:42
+ */
+
+namespace database\core\PDOWrapper;
+
+
+class PDOStatementWrapper extends \PDOStatement
+{
+    private $statement;
+    private $parameters;
+    private $connexion;
+
+    public function __construct($statement, PDOWrapper $connexion)
+    {
+        $this->statement = $statement;
+        $this->connexion = $connexion;
+
+
+    }
+
+    public function execute($input_parameters = [])
+    {
+		$this->parameters = $input_parameters;
+		$this->connexion->stackStatement($this);
+        return true;
+    }
+
+    /**
+     * @return string
+     */
+    public function getStatement()
+    {
+        return $this->statement;
+    }
+
+    /**
+     * @return array
+     */
+    public function getParameters()
+    {
+        return $this->parameters;
+    }
+
+
+
+}
\ No newline at end of file
diff --git a/build/database/core/PDOWrapper/PDOWrapper.php b/build/database/core/PDOWrapper/PDOWrapper.php
new file mode 100644
index 0000000..5674744
--- /dev/null
+++ b/build/database/core/PDOWrapper/PDOWrapper.php
@@ -0,0 +1,147 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: lucas
+ * Date: 30/08/16
+ * Time: 17:26
+ */
+
+namespace database\core\PDOWrapper;
+
+
+class PDOWrapper extends \PDO
+{
+	private $statements = [];
+	private $stacking = false;
+	private $debug = [];
+	private $debugEnabled = false;
+
+    public function __construct(String $dsn, String $username, String $passwd, array $options = [])
+    {
+        parent::__construct($dsn, $username, $passwd, $options);
+    }
+
+    public function prepare($statement, $options = [])
+    {
+    	if($this->debugEnabled){
+			$this->storeDebug();
+		}
+
+        if($this->stacking){
+            return new PDOStatementWrapper($statement, $this);
+        }else{
+			parent::setAttribute(\PDO::ATTR_EMULATE_PREPARES, true);
+        	return parent::prepare($statement, $options);
+
+        }
+    }
+
+    private function storeDebug(){
+    	//get all the debug info about the repo
+		$prepareStack = debug_backtrace(0,3)[1];
+		$stack = debug_backtrace(0,3)[2];
+		//create the reflection object
+		$f = new \ReflectionMethod($stack["class"],$stack["function"]);
+		//get only the repo name
+		$className = explode("\\",$stack["class"]);
+		$className = $className[count($className)-1];
+
+		$result = [];
+
+		//if we are flushing a stack, just count the number of request stacked
+		if($stack["function"] == "executeStack"){
+
+			$result["StackedRequest"] = true;
+			$result["numberOfStackedRequest"] = substr_count($prepareStack["args"][0],";");
+		//if we are not stacking, log the repo call
+		}else if(!$this->stacking){
+			//store results
+			$result["repoName"] = $className;
+			$result["methodName"] = $stack["function"];
+			$result["args"] = [];
+
+			foreach ($f->getParameters() as $key => $param) {
+				$result["args"][$param->name] = $stack["args"][$key];
+			}
+		//else we are stacking a request, we should not log it
+		}else{
+			return;
+		}
+
+		$this->debug[] = $result;
+	}
+	public function getDebug() : array{
+    	return $this->debug;
+	}
+
+    public function enableStacking(){
+    	$this->stacking = true;
+	}
+
+	public function isDebugEnabled() : bool{
+    	return $this->debugEnabled;
+	}
+
+	public function stackStatement(PDOStatementWrapper $st){
+		array_push($this->statements,$st);
+	}
+
+	public function enableDebug(){
+    	$this->debugEnabled = true;
+	}
+
+	public function disableDebug(){
+		$this->debugEnabled = false;
+	}
+
+	public function executeStack(){
+		//init the statements and the generator of number
+		$finalStatement = '';
+		$finalExecute = [];
+		$i = 0;
+
+		//for each request stacked
+		foreach ($this->statements as $request){
+			$statement = $request->getStatement();
+
+			// we have to modify the parameters index at the same time that we modify the request, so we use static class attribute
+			$tempParametes = $request->getParameters();
+
+			//find the given pattern in the request, then call our function and replace the matched string by the return value of our function
+			$finalStatement .= rtrim(preg_replace_callback("/(:[a-z_\-0-9]*)/is",function($matches) use (&$i,&$tempParametes){
+					//get next number
+					$i++;
+
+					//delete the ':' at the beginning of the string
+					$tempKey = ltrim($matches[0],':');
+
+					//copy the parameter with the modified index
+					$tempParametes[$tempKey.$i] = $tempParametes[$tempKey];
+
+					//delete the old index
+					unset($tempParametes[$tempKey]);
+
+					//return the modified string for replacement
+					return $matches[0].$i;
+				},$statement),';').';';
+
+			$finalExecute = array_merge($finalExecute,$tempParametes);
+		}
+
+		//disable stacking
+		$this->stacking = false;
+
+		$this->beginTransaction();
+
+		$req = $this->prepare($finalStatement);
+
+		$success = $req->execute($finalExecute);
+		//as we execute multiple query that we don't fetch, we have to close the cursor if we want to do other requests later
+		$req->closeCursor();
+		$this->commit();
+		//using beginTransaction/commit disable the autocommit, we re-activate it
+		$this->setAttribute(\PDO::ATTR_AUTOCOMMIT,1);
+		parent::setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
+		return $success;
+	}
+}
\ No newline at end of file
diff --git a/build/database/core/Repo.php b/build/database/core/Repo.php
index 6a09828..d5d86f3 100644
--- a/build/database/core/Repo.php
+++ b/build/database/core/Repo.php
@@ -12,6 +12,7 @@
 
 	namespace database\core;
 
+	use database\core\PDOWrapper\PDOWrapper;
 	use \error\core\Error;
 	use \error\core\Err;
 
@@ -20,6 +21,9 @@
 
 		/* (1) Driver
 		---------------------------------------------------------*/
+		/**
+		 * @var DatabaseDriver
+		 */
 		private static $driver = null;
 
 		public static function setDriver(DatabaseDriver $driver){ self::$driver = $driver; }
@@ -57,6 +61,22 @@
 			return $instance;
 		}
 
+		public static function enableStacking(){
+			static::$driver->enableStacking();
+		}
+
+		public static function flushStack(){
+			static::$driver->flushStack();
+		}
+
+		public static function getDebug() : array{
+			return static::$driver->getDebug();
+		}
+
+		public static function isDebugEnabled() : bool{
+			return static::$driver->isDebugEnabled();
+		}
+
 
 
 
diff --git a/config/database-driver.json b/config/database-driver.json
index fb2da3c..0c99f5d 100755
--- a/config/database-driver.json
+++ b/config/database-driver.json
@@ -4,7 +4,8 @@
 			"host"     : "mariadb",
 			"dbname"   : "vhost",
 			"user"     : "php",
-			"password" : "4JB1dtbrIC8pT935"
+			"password" : "4JB1dtbrIC8pT935",
+			"debug"    : true
 		},
 		"remote": {
 			"host"     : "db_remote_host",