java - 试图了解如何将变量插入 jdbc sql 查询中？

Question

我正在尝试将变量插入到java中的sql语句中。我读过另一篇文章Inserting variable into SQL query from Java但我不太明白他们做了什么。

   public static void searchordernumber(int inputnum) {
        try {
            Connection connection = DriverManager.getConnection(url);
            String sql = "SELECT * FROM orderTable WHERE ordernumber=?";
            Statement stmt = connection.createStatement();
            //ResultSet rs = stmt.executeQuery(sql);
            System.out.println("works");
            connection.close();
        } catch (SQLException e) {
            System.out.println(e.getMessage());
        }
    }

如何将 inputnum 变量放在哪里？是？

Answer 1

要将参数绑定(bind)到 SQL 语句中的 ? 占位符，请使用 PreparedStatment。请参阅Using Prepared Statements文档，或多或少如下:

String sql = "SELECT * FROM orderTable WHERE ordernumber = ?";
int orderNumber = 123;
PreparedStatement stmt = con.prepareStatement(sql);
stmt.setInt(1, orderNumber); 
ResultSet resultSet = preparedStatement.executeQuery();