看不懂了，翻译下
string sql = "select mC_cardName,mI_memberNumber,mI_memberName,mC_cardBalance,mC_saleCardMoney from tb_memberCard mc,tb_memberInformation mi where mc.mI_memberInformationId=mi.mI_memberInformationId and mC_cardNumber='" + mC_cardNumber1.Text + "'and mC_password='" + textBox2.Text + "'";



------解决方案--------------------
这就是一句查询语句…… 双表查询…………