+<?php
+
+namespace Drupal\drupalmoduleupgrader\Plugin\DMU\Converter\Functions;
+
+use Drupal\drupalmoduleupgrader\TargetInterface;
+use Pharborist\Functions\FunctionCallNode;
+use Pharborist\Types\StringNode;
+
+/**
+ * @Converter(
+ * id = "_db",
+ * deriver = "\Drupal\drupalmoduleupgrader\Plugin\DMU\Converter\Functions\DBDeriver"
+ * )
+ */
+class DB extends FunctionCallModifier {
+
+ /**
+ * Tables which will cause the function call to be commented out.
+ *
+ * @var string[]
+ */
+ protected static $forbiddenTables = ['system', 'variable'];
+
+ /**
+ * {@inheritdoc}
+ */
+ public function rewrite(FunctionCallNode $call, TargetInterface $target) {
+ $table = $call->getArgumentList()->getItem(0);
+ return ($table instanceof StringNode && in_array($table->toValue(), self::$forbiddenTables)) ? NULL : $call;
+ }
+
+}