The stock transaction database contains a lot of sensitive information in stock exchange. It is very important to guarantee privacy of the account and database when the user queries the database. The asymmetric quantum key distribution(QKD) and its excellent properties are analyzed. An oblivious set-element mapping decision protocol is proposed based on asymmetric QKD. The protocol ensures the privacy of both the user and database when querying the database. Security analysis results show that the protocol can effectively resist the quantum memory attack, fake quantum state attack and entangle-and-measure attack. It has a high channel loss tolerance.