diff --git a/lib/Tools/DbHelper.php b/lib/Tools/DbHelper.php
new file mode 100644
index 0000000..55f7e55
--- /dev/null
+++ b/lib/Tools/DbHelper.php
@@ -0,0 +1,127 @@
+<?php
+namespace OCA\NCDownloader\Tools;
+
+class DbHelper
+{
+    //@var OC\DB\ConnectionAdapter
+    private $conn;
+    private $table = "ncdownloader_info";
+
+    public function __construct()
+    {
+        $this->conn = \OC::$server->getDatabaseConnection();
+        $this->queryBuilder = $this->conn->getQueryBuilder();
+        $this->prefixedTable = $this->queryBuilder->getTableName($this->table);
+        //$container = \OC::$server->query(\OCP\IServerContainer::class);
+        //Helper::debug(get_class($container->query(\OCP\RichObjectStrings\IValidator::class)));
+        //$this->conn = \OC::$server->query(Connection::class);//working only with 22
+        //$this->connAdapter = \OC::$server->getDatabaseConnection();
+        //$this->conn = $this->connAdapter->getInner();
+    }
+
+    public function insert($insert)
+    {
+        $inserted = (bool) $this->conn->insertIfNotExist('*PREFIX*' . $this->table, $insert, [
+            'gid',
+        ]);
+        return $inserted;
+    }
+    public function getAll()
+    {
+        //OC\DB\QueryBuilder\QueryBuilder
+        $queryBuilder = $this->queryBuilder
+            ->select('filename', 'type', 'gid', 'timestamp', 'status')
+            ->from($this->table)
+            ->execute();
+        return $queryBuilder->fetchAll();
+    }
+
+    public function getByUid($uid)
+    {
+        $queryBuilder = $this->queryBuilder
+            ->select('*')
+            ->from($this->table)
+            ->where('uid = :uid')
+            ->setParameter('uid', $uid)
+            ->execute();
+        return $queryBuilder->fetchAll();
+    }
+
+    public function getUidByGid($gid)
+    {
+        $queryBuilder = $this->queryBuilder
+            ->select('uid')
+            ->from($this->table)
+            ->where('gid = :gid')
+            ->setParameter('gid', $gid)
+            ->execute();
+        return $queryBuilder->fetchColumn();
+    }
+
+    public function getYoutubeByUid($uid)
+    {
+        $qb = $this->queryBuilder
+            ->select('*')
+            ->from($this->table)
+            ->where('uid = :uid')
+            ->andWhere('type = :type')
+            ->setParameter('uid', $uid)
+            ->setParameter('type', Helper::DOWNLOADTYPE['YOUTUBE-DL'])
+            ->execute();
+        return $qb->fetchAll();
+    }
+
+    public function getByGid($gid)
+    {
+        $queryBuilder = $this->queryBuilder
+            ->select('*')
+            ->from($this->table)
+            ->where('gid = :gid')
+            ->setParameter('gid', $gid)
+            ->execute();
+        return $queryBuilder->fetch();
+    }
+
+    public function save(array $keys, $values = array(), $conditions = array())
+    {
+        return $this->conn->setValues($this->table, $keys, $values, $conditions);
+    }
+
+    public function deleteByGid($gid)
+    {
+        $qb = $this->queryBuilder
+            ->delete($this->table)
+            ->where('gid = :gid')
+            ->setParameter('gid', $gid);
+        return $qb->execute();
+    }
+    public function executeUpdate($sql, $values)
+    {
+        return $this->conn->executeUpdate($sql, $values);
+    }
+
+    public function updateStatus($gid, $status = 1)
+    {
+        $query = $this->queryBuilder;
+        $query->update($this->table)
+            ->set("status", $query->createNamedParameter($status))
+            ->where('gid = :gid')
+            ->setParameter('gid', $gid);
+        return $query->execute();
+        //$sql = sprintf("UPDATE %s set status = ? WHERE gid = ?", $this->prefixedTable);
+        //$this->execute($sql, [$status, $gid]);
+    }
+
+    public function updateFilename($gid, $filename)
+    {
+        $query = $this->queryBuilder;
+        $query->update($this->table)
+            ->set("filename", $query->createNamedParameter($filename))
+            ->where('gid = :gid')
+            ->andWhere('filename = :filename')
+            ->setParameter('gid', $gid)
+            ->setParameter('filename', 'unknown');
+        return $query->execute();
+    }
+
+}