diff --git a/code/web/private_php/ams/autoload/dblayer.php b/code/web/private_php/ams/autoload/dblayer.php
index 589a88e57..91d260fc3 100644
--- a/code/web/private_php/ams/autoload/dblayer.php
+++ b/code/web/private_php/ams/autoload/dblayer.php
@@ -135,13 +135,12 @@ class DBLayer {
 			$sth -> execute();
 			$lastId = $this -> PDO -> lastInsertId();
 			$this -> PDO -> commit();
-			}
-		catch ( Exception $e )
-		{
+		}
+		catch ( Exception $e ) {
 			// for rolling back the changes during transaction
-			$this -> PDO -> rollBack();
-			throw new Exception( "error in inseting" );
-			}
+			// $this -> PDO -> rollBack();
+			throw $e; // new Exception( "error in inseting" );
+		}
 		return $lastId;
 	}
 
@@ -158,14 +157,11 @@ class DBLayer {
 	public function selectWithParameter( $param, $tb_name, $data, $where ) {
 		$this->useDb();
 		try {
-			$sth = $this -> PDO -> prepare( "SELECT $param FROM $tb_name WHERE $where" );
-			$this -> PDO -> beginTransaction();
-			$sth -> execute( $data );
-			$this -> PDO -> commit();
+			$sth = $this->PDO->prepare( "SELECT $param FROM $tb_name WHERE $where" );
+			$sth->execute( $data );
 		}
 		catch ( Exception $e ) {
-			$this -> PDO -> rollBack();
-			throw new Exception( "error selection" );
+			throw $e; // new Exception( "error selection" );
 			return false;
 		}
 		return $sth;
@@ -180,22 +176,18 @@ class DBLayer {
 	* @param string $where where to select in format('fieldname=:fieldname' AND ...).
 	* @return statement object.
 	*/
-	public function select( $tb_name, $data , $where ) {
+	public function select($tb_name, $data , $where) {
 		$this->useDb();
 		try {
-			$sth = $this -> PDO -> prepare( "SELECT * FROM $tb_name WHERE $where" );
-			$this -> PDO -> beginTransaction();
-			$sth -> execute( $data );
-			$this -> PDO -> commit();
-			}
-		catch( Exception $e )
-		{
-			$this -> PDO -> rollBack();
-			throw new Exception( "error selection" );
-			return false;
-			}
-		return $sth;
+			$sth = $this->PDO->prepare("SELECT * FROM $tb_name WHERE $where");
+			$sth->execute( $data );
 		}
+		catch (Exception $e) {
+			throw $e; // new Exception( "error selection" );
+			return false;
+		}
+		return $sth;
+	}
 
 	/**
 	* Update function with prepared statement.
@@ -208,30 +200,27 @@ class DBLayer {
 	public function update( $tb_name, $data, $where ) {
 		$this->useDb();
 		$field_option_values = null;
-		foreach ( $data as $key => $value )
-		{
+		foreach ( $data as $key => $value ) {
 			$field_option_values .= ",$key" . '=:' . $key;
-			}
+		}
 		$field_option_values = ltrim( $field_option_values, ',' );
 		try {
 			$sth = $this -> PDO -> prepare( "UPDATE $tb_name SET $field_option_values WHERE $where " );
 
-			foreach ( $data as $key => $value )
-			{
+			foreach ( $data as $key => $value ) {
 				$sth -> bindValue( ":$key", $value );
-				}
+			}
 			$this -> PDO -> beginTransaction();
 			$sth -> execute();
 			$this -> PDO -> commit();
 			}
-		catch ( Exception $e )
-		{
-			$this -> PDO -> rollBack();
-			throw new Exception( 'error in updating' );
+		catch ( Exception $e ) {
+			$this->PDO->rollBack();
+			throw $e; // new Exception( 'error in updating' );
 			return false;
-			}
-		return true;
 		}
+	return true;
+	}
 
 	/**
 	* insert function using prepared statements.
@@ -272,14 +261,14 @@ class DBLayer {
 	public function delete( $tb_name, $data, $where ) {
 		$this->useDb();
 		try {
-			$sth = $this -> PDO -> prepare( "DELETE FROM $tb_name WHERE $where" );
-			$this -> PDO -> beginTransaction();
-			$sth -> execute( $data );
-			$this -> PDO -> commit();
+			$sth = $this->PDO->prepare( "DELETE FROM $tb_name WHERE $where" );
+			$this->PDO->beginTransaction();
+			$sth->execute( $data );
+			$this->PDO->commit();
 		}
 		catch (Exception $e) {
-			$this -> PDO -> rollBack();
-			throw new Exception( "error in deleting" );
+			$this->PDO->rollBack();
+			throw $e; // new Exception( "error in deleting" );
 		}
 	}
 }