diff --git a/htdocs/core/db/mssql.class.php b/htdocs/core/db/mssql.class.php
index 5056bf65441..ff5fe8caf0b 100644
--- a/htdocs/core/db/mssql.class.php
+++ b/htdocs/core/db/mssql.class.php
@@ -34,15 +34,15 @@ class DoliDBMssql
 	//! Database handler
 	var $db;
 	//! Database type
-	var $type='mssql';
+	static $type='mssql';
 	//! Database label
-	var $label='MSSQL';
+	static $label='MSSQL';
 	//! Charset used to force charset when creating database
-	var $forcecharset='latin1';
+	static $forcecharset='latin1';
 	//! Collate used to force collate when creating database
-	var $forcecollate='latin1_swedish_ci';
+	static $forcecollate='latin1_swedish_ci';
 	//! Version min database
-	var $versionmin=array(2000);
+	static $versionmin=array(2000);
 	//! Resultset de la derniere requete
 	var $results;
 	//! 1 si connecte, 0 sinon
@@ -772,7 +772,7 @@ class DoliDBMssql
 	 * 	\param			collation		Charset used to sort data
 	 * 	\return	        resource		resource defined if OK, null if KO
 	 * 	\remarks        Ne pas utiliser les fonctions xxx_create_db (xxx=mssql, ...) car elles sont deprecated
-	 *					On force creation de la base avec le charset forcecharset
+	 *					We force to create database with charset this->forcecharset and collate this->forcecollate
 	 */
 	function DDLCreateDb($database,$charset='',$collation='')
 	{
diff --git a/htdocs/core/db/mysql.class.php b/htdocs/core/db/mysql.class.php
index 3cd4f17eb7c..2deea516cd5 100644
--- a/htdocs/core/db/mysql.class.php
+++ b/htdocs/core/db/mysql.class.php
@@ -34,15 +34,15 @@ class DoliDBMysql
 	//! Database handler
 	var $db;
 	//! Database type
-	var $type='mysql';
+	static $type='mysql';
 	//! Database label
-	var $label='MySQL';
+	static $label='MySQL';
 	//! Charset used to force charset when creating database
-	var $forcecharset='utf8';	// latin1, utf8
+	static $forcecharset='utf8';	// latin1, utf8
 	//! Collate used to force collate when creating database
-	var $forcecollate='utf8_general_ci';	// latin1_swedish_ci, utf8_general_ci
+	static $forcecollate='utf8_general_ci';	// latin1_swedish_ci, utf8_general_ci
 	//! Version min database
-	var $versionmin=array(3,1,0);
+	static $versionmin=array(3,1,0);
 	//! Resultset of last request
 	var $results;
 	//! 1 if connected, 0 else
diff --git a/htdocs/core/db/mysqli.class.php b/htdocs/core/db/mysqli.class.php
index 19b2b8fe885..87a1e2f28f5 100644
--- a/htdocs/core/db/mysqli.class.php
+++ b/htdocs/core/db/mysqli.class.php
@@ -34,15 +34,15 @@ class DoliDBMysqli
     //! Database handler
     var $db;
     //! Database type
-    var $type='mysqli';
+    static $type='mysqli';
     //! Database label
-    var $label='MySQL';
+    static $label='MySQL';
     //! Charset used to force charset when creating database
-    var $forcecharset='utf8';	// latin1, utf8
+    static $forcecharset='utf8';	// latin1, utf8
     //! Collate used to force collate when creating database
-    var $forcecollate='utf8_general_ci';	// latin1_swedish_ci, utf8_general_ci
+    static $forcecollate='utf8_general_ci';	// latin1_swedish_ci, utf8_general_ci
     //! Version min database
-    var $versionmin=array(4,1,0);
+    static $versionmin=array(4,1,0);
     //! Resultset of last request
     var $results;
     //! 1 if connected, 0 else
diff --git a/htdocs/core/db/pgsql.class.php b/htdocs/core/db/pgsql.class.php
index a2b600908c2..a5f5d81c3af 100644
--- a/htdocs/core/db/pgsql.class.php
+++ b/htdocs/core/db/pgsql.class.php
@@ -33,11 +33,12 @@
 class DoliDBPgsql
 {
 	var $db;                      // Database handler
-	var $type='pgsql';            // Name of manager
-	var $label='PostgreSQL';      // Label of manager
+	static $type='pgsql';            // Name of manager
+	static $label='PostgreSQL';      // Label of manager
 	//! Charset
-	var $forcecharset='latin1';
-	var $versionmin=array(8,4,0);	// Version min database
+	static $forcecharset='latin1';
+	//! Version min database
+	static $versionmin=array(8,4,0);	// Version min database
 
 	var $results;                 // Resultset de la derniere requete