Question

public static void main(String[] args)
{
    Connection con=null;
    PreparedStatement pstmt=null;
    ResultSet rs=null;
    /*
     * 1.load the driver
     * driver class :com.mysql.jdbc.Driver

     */

    try {
        Driver driverref=new Driver();
        DriverManager.registerDriver(driverref);
        /*
         * 2.get db connection via driver
         */
        String DbUrl="jdbc:mysql://localhost:3306/college?user=suhas&password=j2ee";
        con=DriverManager.getConnection(DbUrl);
        /*
         * 3.issue SQL queries via Connection
         */
        String query="select * from Students_info where regno=?"
         +"firstname=?";
        pstmt=con.prepareStatement(query);
        String regnum=args[0];
        int regno=Integer.parseInt(regnum);
        pstmt.setInt(1,regno);
        pstmt.setString(2, args[1]);
        rs=pstmt.executeQuery();
        /*
         * 4.process the results returned by sql query
         */
        while(rs.next()){
            int dbregno=rs.getInt("regno");
            String fname=rs.getString("firstname");
            String mname=rs.getString("middlename");
            String lname=rs.getString("lastname");
            System.out.println("regno "+dbregno);
            System.out.println("first name "+fname );
            System.out.println("middlename "+mname);
            System.out.println("lastname "+lname);
            }//end of while
    }
    catch (SQLException e) 
    {
        e.printStackTrace();
    }
    finally{
        /*
         * close all jdbc objects
         */
        try {
            if(con!=null){
                con.close();

            }
            if(pstmt!=null){
                pstmt.close();
            }
            if(rs!=null){
                rs.close();
            }
        } catch (SQLException e) {

            e.printStackTrace();
        }
    }
}

} 使用上面的代码我无法在运行配置中传递args值。获取数字格式异常如何解决此问题。如何在运行配置的Arguments选项卡中传递args。

Answer 1

仔细查看您的代码：

String query="select * from Students_info where regno=?"
         +"firstname=?";

完全等同于

String query="select * from Students_info where regno=?firstname=?";

当您用查询参数regno = 1和args[1] = "Gord"替换时，让我们假装。请求的SQL查询如下所示：

select * from Students_info where regno=1firstname='Gord'

这不是有效的语法。需要使用布尔运算符组合WHERE子句中的两个条件：AND或OR。因此，您的原始查询字符串必须是

String query="select * from Students_info where regno=?"
         +" AND firstname=?";

或

String query="select * from Students_info where regno=?"
         +" OR firstname=?";

eclipse中准备好的语句执行

1 个答案: