Fix saving NULL value

This reverts commit ed130065.

Conflicts:
	adminer/drivers/mongo.inc.php
	adminer/include/functions.inc.php

adminer/drivers/mongo.inc.php

@@ -116,10 +116,6 @@ if (isset($_GET["mongo"])) {
 	class Min_Driver extends Min_SQL {
 		public $primary = "_id";
 		
-		function quote($value) {
-			return ($value === null ? $value : parent::quote($value));
-		}
-		
 		function select($table, $select, $where, $group, $order = array(), $limit = 1, $page = 0, $print = false) {
 			$select = ($select == array("*")
 				? array()

adminer/include/driver.inc.php

@@ -10,14 +10,6 @@
 		$this->_conn = $connection;
 	}
 	
-	/** Quote a SQL string or null value
-	* @param string
-	* @return string
-	*/
-	function quote($value) {
-		return ($value === null ? "NULL" : $this->_conn->quote($value));
-	}
-	
 	/** Select data from table
 	* @param string
 	* @param array result of $adminer->selectColumnsProcess()[0]

adminer/include/functions.inc.php

@@ -285,13 +285,13 @@ function get_password() {
 	return $return;
 }
 
-/** Shortcut for $driver->quote($string)
+/** Shortcut for $connection->quote($string)
 * @param string
 * @return string
 */
 function q($string) {
-	global $driver;
-	return $driver->quote($string);
+	global $connection;
+	return $connection->quote($string);
 }
 
 /** Get list of values from database
@@ -937,7 +937,7 @@ function process_input($field) {
 		return ($field["on_update"] == "CURRENT_TIMESTAMP" ? idf_escape($field["field"]) : false);
 	}
 	if ($function == "NULL") {
-		$value = null;
+		return "NULL";
 	}
 	if ($field["type"] == "set") {
 		return array_sum((array) $value);

changes.txt

@@ -4,6 +4,7 @@ Unlock session in alter database
 Make master key unreadable to others (bug #410)
 Fix edit by long non-utf8 string
 Specify encoding for PHP 5.6 with invalid default_charset
+Fix saving NULL value, bug since Adminer 4.0.3
 MySQL: Use utf8mb4 if available
 Elasticsearch: Use where in select
 Danish translation