diff --git a/build/database/repo/professor.php b/build/database/repo/professor.php
index c2f8afa..c4c4d9d 100644
--- a/build/database/repo/professor.php
+++ b/build/database/repo/professor.php
@@ -13,80 +13,238 @@ use database\core\Repo_i;
 
 class professor extends Repo_i {
 
-	public function create(string $lastName, string $firstName, int $category, $hoursToDo = 0, $initials = "", $isAdmin = false , $casLogin = "" ) : int{
-		$st = $this->pdo->prepare("INSERT INTO Professeur (casLogin, lastName, firstName, abreviation, admin,hoursToDo, Categorie_idCategorie)
-											 VALUE (:casLogin, :lastName, :firstName, :abrev, :admin, :hoursToDo, :cat);
-											 ");
 
-		$st->execute([
-			"casLogin" => $casLogin,
-			"lastName" => $lastName,
-			"firstName" => $firstName,
-			"abrev" => $initials,
-			"admin" => $isAdmin? 1 : 0,
-			"hoursToDo" => $hoursToDo,
-			"cat" => $category
+	/* (1) Creates a new professor
+	*
+	* @lastName<String>					The professor's lastName
+	* @firstName<String>				The professor's firstName
+	* @category<int>					The professor's category ID
+	* @hoursToDo<int>					The professor's number of hours to do
+	* @initials<int>					The professor's initials
+	* @isAdmin<bool>					Whether the professor is an admin
+	* @casLogin<String>					The professor's CAS username
+	*
+	* @return prof_id<int>				The professor's UID (or NULL on error)
+	*
+	---------------------------------------------------------*/
+	public function create(string $lastName, string $firstName, int $category, $hoursToDo = 0, $initials = "", $isAdmin = false , $casLogin = "" ) : ?int{
+
+		/* (1) Prepare Statement */
+		$st = $this->pdo->prepare("INSERT INTO
+			Professeur(`casLogin`, `lastName`, `firstName`, `abreviation`, `admin`, `hoursToDo`, `Categorie_idCategorie`)
+			VALUE (:casLogin, :lastName, :firstName, :abrev, :is_admin, :hoursToDo, :cat);");
+
+		/* (2) Bind params and execute */
+		$success = $st->execute([
+			':casLogin'  => $casLogin,
+			':lastName'  => $lastName,
+			':firstName' => $firstName,
+			':abrev'     => $initials,
+			':is_admin'  => $isAdmin ? 1 : 0,
+			':hoursToDo' => $hoursToDo,
+			':cat'       => $category
 		]);
 
+		/* (3) Manage error */
+		if( !$success )
+			return NULL;
+
+		/* (4) Return inserted ID */
 		return $this->pdo->lastInsertId();
+
 	}
 
-	public function exists(string $lastName, string $firstName) : int{
-		$st = $this->pdo->prepare("SELECT idProfesseur FROM Professeur WHERE firstName = :firstName AND lastName = :lastName");
 
-		$st->execute([
-			"firstName" => $firstName,
-			"lastName" => $lastName
+
+	/* (2) Check if a professor exists (by its names)
+	*
+	* @lastName<String>					The professor's lastName
+	* @firstName<String>				The professor's firstName
+	*
+	* @return prof_id<int>				The professor's UID (or NULL on error)
+	*
+	---------------------------------------------------------*/
+	public function exists(string $lastName, string $firstName) : ?int{
+
+		/* (1) Prepare Statement */
+		$st = $this->pdo->prepare("SELECT idProfesseur
+			FROM  Professeur
+			WHERE firstName = :firstName
+			AND   lastName = :lastName");
+
+		/* (2) Bind params and execute */
+		$success = $st->execute([
+			':firstName' => $firstName,
+			':lastName'  => $lastName
 		]);
 
-		return $st->fetch()["idProfesseur"]?: 0;
+		/* (3) Return NULL on error */
+		if( !$success )
+			return NULL;
+
+		/* (4) Return @prof_id or NULL if nothing found */
+		return $st->fetch()['idProfesseur'] ?: NULL;
+
 	}
 
-	public function update(int $id, array $data) : bool{
-		$updSt = "";
 
-		foreach ($data as $key => $field){
-			$updSt .= "$key = :$key,";
-		}
 
-		$updSt = rtrim($updSt,",");
 
-		$st = $this->pdo->prepare("UPDATE Professeur SET $updSt WHERE idProfesseur = :id");
 
-		return $st->execute(array_merge($data,[
-			"id" => $id
-		]));
+	/* (3) Check if a professor exists (by its names)
+	*
+	* @idProf<int>						The professor's UID
+	* @lastName<String>					[OPT] The professor's new lastName
+	* @firstName<String>				[OPT] The professor's new firstName
+	* @category<int>					[OPT] The professor's new category ID
+	* @hoursToDo<int>					[OPT] The professor's new number of hours to do
+	* @initials<int>					[OPT] The professor's new initials
+	* @isAdmin<bool>					[OPT] Whether the professor is an admin
+	* @casLogin<String>					[OPT] The professor's new CAS username
+	*
+	* @return updated<bool>				Whether the updated have been successful
+	*
+	---------------------------------------------------------*/
+	public function update(int $id, ?String $lastName, ?String $firstName, ?int $category, ?int $hoursToDo, ?String $initials, ?bool $isAdmin, ?String $casLogin) : bool{
+
+		/* (1) Build request */
+		$build_rq   = [];
+		$bind_param = [ ':idProfesseur' => $id ];
+
+		if( !is_null($lastName)  ){ $build_rq[] = '`lastName`  = :lastName';  $bind_param[':lastName']  = $lastName;  }
+		if( !is_null($firstName) ){ $build_rq[] = '`firstName` = :firstName'; $bind_param[':firstName'] = $firstName; }
+		if( !is_null($category)  ){ $build_rq[] = '`category`  = :category';  $bind_param[':category']  = $category;  }
+		if( !is_null($hoursToDo) ){ $build_rq[] = '`hoursToDo` = :hoursToDo'; $bind_param[':hoursToDo'] = $hoursToDo; }
+		if( !is_null($initials)  ){ $build_rq[] = '`initials`  = :initials';  $bind_param[':initials']  = $initials;  }
+		if( !is_null($isAdmin)   ){ $build_rq[] = '`isAdmin`   = :isAdmin';   $bind_param[':isAdmin']   = $isAdmin;   }
+		if( !is_null($casLogin)  ){ $build_rq[] = '`casLogin`  = :casLogin';  $bind_param[':casLogin']  = $casLogin;  }
+
+		/* (2) ERROR if no updated field */
+		if( count($build_rq) <= 0 || count($bind_param) <= 1 )
+			return FALSE;
+
+		/* (3) Build request */
+		$sql_rq = "UPDATE `Professeur` SET ".implode(', ', $build_rq)." WHERE `idProfesseur` = :idProfesseur";
+
+		/* (4) Prepare statement */
+		$st = $this->pdo->prepare($sql_rq);
+
+		/* (5) Return execution success */
+		return $st->execute($bind_param);
+
 	}
 
+
+
+
+	/* (4) Return whether a professor is an admin
+	*
+	* @idProf<int>						The professor's UID
+	*
+	* @return is_admin<bool>			Whether the professor is an admin (FALSE if does not exist)
+	*
+	---------------------------------------------------------*/
 	public function isAdmin(int $id) : bool{
-		$st = $this->pdo->prepare("SELECT admin FROM Professeur WHERE idProfesseur = :id");
 
-		$st->execute([
-			"id" => $id
-		]);
+		/* (1) Prepare statement */
+		$st = $this->pdo->prepare("SELECT `admin` FROM `Professeur` WHERE `idProfesseur` = :id AND `admin` = 1");
 
-		return $st->fetch()["admin"] == 1;
+		/* (2) Bind params and execute statement */
+		$success = $st->execute([ ':id' => $id ]);
+
+		/* (3) FALSE on error */
+		if( !$success )
+			return FALSE;
+
+		/* (4) Return whether we have a result or not */
+		return $st->fetch() == 1;
 	}
 
-	public function get(int $id) : array{
-		$st = $this->pdo->prepare("SELECT * FROM Professeur WHERE idProfesseur = :id");
 
-		$st->execute([
-			"id" => $id
-		]);
 
-		return $st->fetch();
+
+	/* (5) Gets a professor by its UID
+	*
+	* @idProf<int>						The professor's UID
+	*
+	* @return teacher<array>			The professor's data (NULL on error / not found)
+	*
+	---------------------------------------------------------*/
+	public function get(int $id) : ?array{
+
+		/* (1) Prepare Statement */
+		$st = $this->pdo->prepare("SELECT * FROM `Professeur` WHERE `idProfesseur` = :id");
+
+		/* (2) Bind params and execute statement */
+		$success = $st->execute([ ':id' => $id ]);
+
+		/* (3) Manage error */
+		if( !$success )
+			return NULL;
+
+		/* (4) Get data */
+		$fetched = $st->fetch();
+
+		/* (5) Return NULL on no result */
+		if( $fetched === false )
+			return NULL;
+
+		/* (6) Return data */
+		return $fetched;
+
 	}
 
+
+
+
+	/* (6) Gets all professors
+	*
+	* @return teachers<array>			The professors' data ([] on error)
+	*
+	---------------------------------------------------------*/
+	public function getAll() : array{
+
+		/* (1) Set query */
+		$query = $this->pdo->query("SELECT * FROM `Professeur` ORDER BY `abreviation` ASC");
+
+		/* (2) If error return empty array */
+		if( $query === false )
+			return [];
+
+		/* (3) Return fetched data */
+		return $query->fetchAll();
+
+	}
+
+
+
+
+	/* (7) Deletes a professor
+	*
+	* @return deleted<bool>				Whether the professor have been deleeted successfully
+	*
+	---------------------------------------------------------*/
 	public function delete(int $id) : bool{
-		$st = $this->pdo->prepare("DELETE FROM Professeur WHERE idProfesseur = :id");
 
-		return $st->execute([
-			"id" => $id
-		]);
+		/* (1) Prepare statement */
+		$st = $this->pdo->prepare("DELETE FROM `Professeur` WHERE `idProfesseur` = :id");
+
+		/* (2) Return the execution status */
+		return $st->execute([ ':id' => $id ]);
+
 	}
 
+
+
+
+	/* (8) Returns a professor's statistic data
+	*
+	* @return data<array>				Professor data
+	*
+	---------------------------------------------------------*/
 	public function getVH(int $id) : array{
+
+		/* (1) Prepare Statement */
 		$st = $this->pdo->prepare("SELECT VHCours, VHTd, VHTp, Cat.idCategorie idCat, Prof.hoursToDo du
 											FROM Professeur Prof, Categorie Cat,
 											  (SELECT IFNULL(SUM(Cours.volume),0) VHCours, Prof.idProfesseur idProf FROM Professeur Prof LEFT JOIN Cours ON Prof.idProfesseur = Cours.Professeur_idProfesseur GROUP BY Prof.idProfesseur) VHCours,
@@ -98,11 +256,17 @@ class professor extends Repo_i {
 											   VHCours.idProf = Prof.idProfesseur AND
 											   VHTp.idProf = Prof.idProfesseur AND
 											   VHTd.idProf = Prof.idProfesseur;");
-		$st->execute([
-			"idProf" => $id
-		]);
 
+		/* (2) Bind params and execute */
+		$success = $st->execute([ ':idProf' => $id ]);
+
+		/* (3) Manage error */
+		if( !$success )
+			return [];
+
+		/* (4) Return data */
 		return $st->fetch() ?: [];
+
 	}
 
 }
\ No newline at end of file