Fixed batch insert with empty rows;

Author: edgardmessias

src/QueryBuilder.php

@@ -282,6 +282,10 @@ public function update($table, $columns, $condition, &$params)
      */
     public function batchInsert($table, $columns, $rows)
     {
+        if (empty($rows)) {
+            return '';
+        }
+
         $schema = $this->db->getSchema();
         if (($tableSchema = $schema->getTableSchema($table)) !== null) {
             $columnSchemas = $tableSchema->columns;