Fix that the sql port does not change when updating the type of the database

fixes #7491

application/forms/Config/Resource/DbResourceForm.php

@@ -49,6 +49,7 @@ class DbResourceForm extends Form
             'db',
             array(
                 'required'      => true,
+                'autosubmit'    => true,
                 'label'         => $this->translate('Database Type'),
                 'description'   => $this->translate('The type of SQL database'),
                 'multiOptions'  => $dbChoices
@@ -69,9 +70,10 @@ class DbResourceForm extends Form
             'port',
             array(
                 'required'          => true,
+                'preserveDefault'   => true,
                 'label'             => $this->translate('Port'),
                 'description'       => $this->translate('The port to use'),
-                'value'         => 3306
+                'value'             => ! array_key_exists('db', $formData) || $formData['db'] === 'mysql' ? 3306 : 5432
             )
         );
         $this->addElement(