diff --git a/DBEngine.h b/DBEngine.h
index 878a42e..82d444e 100755
--- a/DBEngine.h
+++ b/DBEngine.h
@@ -20,6 +20,7 @@ public:
 	void saveToFile(vector<string> cmds);
 	Relation selection(string attName, string s, Relation r);
 	Relation projection(vector<string> input, Relation r);
+	Relation product(string s1, Relation r1, Relation r2);
 	void rename(Relation& r, vector<string> oldnames, vector<string> newnames);
 	Relation setUnion(Relation r1, Relation r2);
 	//void setDiff();