diff --git a/src/Database/Mysql/Mysql.php b/src/Database/Mysql/Mysql.php
index d80250d..421c274 100644
--- a/src/Database/Mysql/Mysql.php
+++ b/src/Database/Mysql/Mysql.php
@@ -61,7 +61,7 @@ public function query($statement,  $fetchAll = true, $fetchMode = 'obj')
         $this->sqlQuery =  $this->pdo
                                 ->query($statement);
 
-        if (isset($this->sqlQuery)) {
+        if (isset($this->sqlQuery) && !is_bool($this->sqlQuery)) {
             $this->rowCount =  $this->sqlQuery
                                     ->rowCount();
 
@@ -97,7 +97,7 @@ public function prepare($statement, array $attributes, $fetchAll = true, $fetchM
         $executeResponse = $this->sqlQuery
                                 ->execute($attributes);
 
-        if (isset($this->sqlQuery)) {
+        if (isset($this->sqlQuery) && !is_bool($this->sqlQuery)) {
             $this->rowCount =  $this->sqlQuery
                                     ->rowCount();
 
diff --git a/src/Query/Query.php b/src/Query/Query.php
index 498805b..8c390eb 100644
--- a/src/Query/Query.php
+++ b/src/Query/Query.php
@@ -103,7 +103,7 @@ public function get(array $fetchAttributes = null, array $executeAttributes = nu
     public function exec()
     {
         try {
-            return $this->query($this->sqlQuery, $this->sqlAttributes, false);
+            return $this->query($this->sqlQuery, empty($this->sqlAttributes) ? ['all'] : $this->sqlAttributes, false);
         } catch (Exception $e) {
             return [$e->getMessage()];
         }
@@ -135,6 +135,17 @@ public function orderBy($orders)
         return $this;
     }
 
+     public function groupBy($groups)
+    {
+        foreach ($groups as $value) {
+            $queryGroups[] = $value;
+        }
+
+        $this->sqlQuery .=' GROUP BY '.implode(',', $queryGroups);
+
+        return $this;
+    }
+
     public function where($conditions, $or = false)
     {
         foreach ($conditions as $key => $value) {
@@ -145,7 +156,7 @@ public function where($conditions, $or = false)
             }
         }
 
-        if (isset($or)) {
+        if (isset($or) && $or !== false) {
             $this->sqlQuery .= ' WHERE '.implode(' OR ', $fieldConditions);
 
             return $this;
@@ -198,4 +209,9 @@ public function close()
     {
         return $this->pdo->disconnect();
     }
+
+    public function error()
+    {
+        return $this->pdo->get();
+    }
 }