Question

我目前正在研究java的更新声明。单击button后，它将获取您放入textfield的整数数据，它将从下拉列表中读取名称并提供相应的员工ID。数据库连接通过不同的类完成。

    ActionListener myActionListener = new ActionListener() {
        public void actionPerformed(ActionEvent ae) {
            DatabaseConnection connection = new DatabaseConnection();
            if (connection.openConnection()) {
                String ID = input1.getText();
                int orderID = Integer.parseInt(ID);

                String firstName = (String) cb.getSelectedItem();
                System.out.println(firstName);
                System.out.println(orderID);
                if (firstName == "Patrick") {
                    int employeeId = 10;
                    String sql = "UPDATE barorder SET statusId=2, employeeId='" + employeeId + "' where id='" + orderID + "' ;";
                }

            }
        }
    };

这是我到目前为止所得到的，但我现在不知道如何执行SQL String。有什么建议吗？

Answer 1

您可以使用PreparedStatement更新查询，如下所示：

  ActionListener myActionListener = new ActionListener()
    {
        public void actionPerformed(ActionEvent ae)
        {
            DatabaseConnection connection = new DatabaseConnection();
            PreparedStatement preparedStatement = null;
            if (connection.openConnection())
            {
                String ID = input1.getText();
                int orderID = Integer.parseInt(ID);

                String firstName = (String) cb.getSelectedItem();
                System.out.println(firstName);
                System.out.println(orderID);
                if (firstName == "Patrick")
                {
                    int employeeId = 10;

                    String sql = "UPDATE barorder SET statusId=2, employeeId= ? where id= ?";
                    preparedStatement = connection.prepareStatement(sql);
                    preparedStatement.setInt(1, employeeId);
                    preparedStatement.setInt(2, orderID);
                    preparedStatement.executeUpdate(sql);

                }

            }
        }
    };

Answer 2

使用PreparedStatement可以解决您的问题。

在我自己的项目中，我使用了这个

        PreparedStatement prep = conn.prepareStatement("INSERT INTO Signup(Username, password, Email) VALUES(?, ?, ?)");
        prep.setString(1, UserName);
        prep.setString(2, Password);
        prep.setString(3, Email);

        prep.executeUpdate();

您可以从链接获得帮助：http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html

执行和sql字符串

2 个答案: