diff --git a/inc/db.php b/inc/db.php
index 7ac7a67..449a701 100644
--- a/inc/db.php
+++ b/inc/db.php
@@ -37,14 +37,14 @@ class Db extends PhpObject
 	 * 			'cascading_delete'=>array('table_name1'=>array('linked_table1', 'linked_table2', ...), 'table_name2'=>...))
 	 * @var Array
 	 */
-	public function __construct($sDbServer, $sLogin, $sPass, $sDatabase, $asOptions, $sEncoding='utf8mb4')
+	public function __construct($sDbServer, $sLogin, $sPass, $sDatabase, $asOptions, $sEncoding='utf8mb4', $sTimeZone='Europe/Paris')
 	{
 		parent::__construct(__FILE__, Settings::DEBUG);
 		$this->sDatabase = $sDatabase;
 		$this->asOptions = $asOptions;
 		//$this->oConnection = mysql_connect(self::DB_SERVER, self::DB_LOGIN, self::DB_PASS);
 		$this->oConnection = new mysqli($sDbServer, $sLogin, $sPass);
-		$this->syncPhpParams($sEncoding);
+		$this->syncPhpParams($sEncoding, $sTimeZone);
 
 		/*
 		 $dsn = 'mysql:dbname='.$this->sDatabase.';host='.self::DB_SERVER;
@@ -73,20 +73,13 @@ class Db extends PhpObject
 		}
 	}
 
-	private function syncPhpParams($sEncoding)
+	private function syncPhpParams($sEncoding, $sTimeZone)
 	{
 		//Characters encoding
 		$this->oConnection->set_charset($sEncoding); //SET NAMES
 
-		//Time zone
-		$oNow = new DateTime();
-		$iMins = $oNow->getOffset() / 60;
-		$iSign = ($iMins < 0)?-1:1;
-		$iMins = abs($iMins);
-		$iHours = floor($iMins / 60);
-		$iMins -= $iHours * 60;
-		$sOffset = sprintf('%+d:%02d', $iHours*$iSign, $iMins);
-		$this->setQuery("SET time_zone='{$sOffset}';");
+		//Timezone
+		$this->setQuery("SET time_zone='{$sTimeZone}';");
 	}
 
 	public function __destruct()
@@ -210,7 +203,7 @@ class Db extends PhpObject
 		$asForeignKeyQueries = array();
 		foreach($asTableNames as $sTableName)
 		{
-			$asTableColumns = array_keys($this->getTablecolumns($sTableName));
+			$asTableColumns = $this->getTablecolumns($sTableName, false);
 			foreach($asTableColumns as $sColumnName)
 			{
 				if($this->isId($sColumnName) && $sColumnName!=self::getId($sTableName))
@@ -313,10 +306,11 @@ class Db extends PhpObject
 	private function isField($sTableFieldName)
 	{
 		$asPath = explode('.', str_replace('`', '', $sTableFieldName));
-		return (is_array($asPath) 
-				&& count($asPath)==2
-				&& in_array($asPath[0], $this->getTables()) //table among the declared tables
-				&& in_array($asPath[1], array_keys($this->getTablecolumns($asPath[0])))); //field among the table fields
+		return (
+			is_array($asPath) 
+			&& count($asPath)==2
+			&& $this->isColumnInTable($asPath[0], $asPath[1])
+		);
 	}
 
 	private function getTable($sTableId)
@@ -331,7 +325,7 @@ class Db extends PhpObject
 		}
 	}
 
-	public function getTablecolumns($sTableName)
+	public function getTablecolumns($sTableName, $bTypes=true)
 	{
 		if(!array_key_exists($sTableName, $this->asOptions['tables'])) return false;
 		
@@ -339,9 +333,16 @@ class Db extends PhpObject
 		foreach($this->asOptions['tables'][$sTableName] as $sFieldName) $asTableColumns[] = $sFieldName;
 		$asTableColumns[] = 'led';
 		
+		if(!$bTypes) return $asTableColumns;
+		
 		$asTableName = array_fill(0, count($asTableColumns), $sTableName);
 		return array_combine($asTableColumns, array_map(array('self', 'getColumnType'), $asTableColumns, $asTableName));
 	}
+	
+	public function isColumnInTable($sTableName, $sColName) {
+		$asCols = $this->getTablecolumns($sTableName, false);
+		return ($asCols && in_array($sColName, $asCols));
+	}
 
 	private function getColumnType($sColumnName, $sTableName)
 	{
diff --git a/inc/main.php b/inc/main.php
index 6c8dbc4..23a1fa4 100755
--- a/inc/main.php
+++ b/inc/main.php
@@ -63,11 +63,12 @@ abstract class Main extends PhpObject
 		if($bDb) $asMandatoryClasses[] = array('name'=>'db', 'project'=>false);
 		foreach($asMandatoryClasses as $asClass) $this->oClassManagement->incClass($asClass['name'], $asClass['project']);
 		
+		$sTimeZone = ($sTimeZone=='')?Settings::TIMEZONE:$sTimeZone;
 		$this->setContext($sProcessPage, $sTimeZone);
 
 		//Init objects
 		if($bDb) {
-			$this->oDb = new Db(Settings::DB_SERVER, Settings::DB_LOGIN, Settings::DB_PASS, Settings::DB_NAME, $this->getSqlOptions() , Settings::DB_ENC);
+			$this->oDb = new Db(Settings::DB_SERVER, Settings::DB_LOGIN, Settings::DB_PASS, Settings::DB_NAME, $this->getSqlOptions() , Settings::DB_ENC, $sTimeZone);
 			if(in_array($this->oDb->sDbState, array(Db::DB_NO_DATA, Db::DB_NO_TABLE))) $this->install();
 		}
 	}
@@ -81,7 +82,7 @@ abstract class Main extends PhpObject
 	private function setContext($sProcessPage, $sTimeZone='')
 	{
 		//Browser <> PHP <> MySql synchronization
-		date_default_timezone_set(($sTimeZone=='')?Settings::TIMEZONE:$sTimeZone);
+		date_default_timezone_set($sTimeZone);
 		ini_set('default_charset', Settings::TEXT_ENC);
 		header('Content-Type: text/html; charset='.Settings::TEXT_ENC);
 		mb_internal_encoding(Settings::TEXT_ENC);