想要显示所有问题和选项 [英] Want to display all question and options

问题描述

我希望它显示问题到目前为止我已经制作了一个数组,,, thnx



我尝试了什么：

i want it to display question so far i have made an array ,,, thnx

What I have tried:

private void SelectedIndexChanged(object sender, EventArgs e)
        {
            

                SqlConnection conn = new SqlConnection();
                string cmdText = "my command";

                SqlDataAdapter da = new SqlDataAdapter(cmdText, conn);

                SqlCommand cmd = new SqlCommand(cmdText, conn);
                conn.ConnectionString = constring;

                try
                {
                    conn.Open();
                    
                    SqlDataReader rd = cmd.ExecuteReader();

                    
                        {
                            textBox1.Text = (rd["Question"].ToString());

                            radioButton4.Text = rd["opt4"].ToString();
                            radioButton1.Text = rd["opt1"].ToString();
                            radioButton2.Text = rd["opt2"].ToString();
                            radioButton3.Text = rd["opt3"].ToString();

                        }

                    }

                }
                catch (Exception exp)
                {
                    MessageBox.Show(exp.ToString());
                }
                finally
                {
                    conn.Close();
                }

            }

        }

推荐答案

- 查看关于SQL注入攻击漏洞的评论。永远不要使用连接字符串来创建SQL命令，而是使用参数化查询（如下所示）。



- 没有必要乱搞数组，只需保留在DataTable中读取数据库的结果。



- 使用使用作为SqlConnection和SqlCommand实现IDisposable。



- 将读取数据库的问题从填充UI中分离出来



我可能会做这样的事情（警告 - 这是未经测试的）

- See the comments about vulnerability to SQL Injection attacks. Never use concatenated strings to create your SQL command, use Parameterised queries instead (like below).

- There is no need to mess around with an array, just keep the results of the database read in a DataTable.

- Make use of using as SqlConnection and SqlCommand implement IDisposable.

- Separate the concerns of reading the database from populating the UI

I would probably do something like this (caveat - this is untested)

private DataTable quest = new DataTable();
private int lastQuest = -1;
  private DataTable GetQuestions(string difficulty, string subject)
  {
      //If one of the inputs is empty return the list of questions we currently have
      if (string.IsNullOrEmpty(difficulty) || string.IsNullOrEmpty(subject)) return quest;

      var dt = new DataTable();
      const string cmdText = "SELECT Question,Opt1,Opt2,Opt3,Opt4 from Questions where DiffLevel=@diff AND SubName= @subj";
      using (var conn = new SqlConnection(constring))
      {
          conn.Open();

          using(var cmd = new SqlCommand(cmdText, conn))
          {
              cmd.Parameters.AddWithValue("@diff", difficulty);
              cmd.Parameters.AddWithValue("subj", subject);

              var dr = cmd.ExecuteReader();
              dt.Load(dr);
          }

          conn.Close();
      }
      return dt;
  }

  private void PopulateQuestion(int questNo)
  {
      if (questNo > quest.Rows.Count - 1 || questNo < 0 ) return;

      textBox1.Text = quest.Rows[questNo]["Question"].ToString();
      lastQuest = questNo;  //NOTICE THIS !!
      radioButton1.Text = quest.Rows[questNo]["opt1"].ToString();
      radioButton2.Text = quest.Rows[questNo]["opt2"].ToString();
      radioButton3.Text = quest.Rows[questNo]["opt3"].ToString();
      radioButton4.Text = quest.Rows[questNo]["opt4"].ToString();
  }

  private void difflevel_SelectedIndexChanged(object sender, EventArgs e)
  {
      HandleIndexChanged();
  }

  private void subj_SelectedIndexChanged(object sender, EventArgs e)
  {
      HandleIndexChanged();
  }
  private void HandleIndexChanged()
  {
      quest = GetQuestions(difflevel.SelectedItem.ToString(), subj.SelectedItem.ToString());

      if (quest.Rows.Count > 0)
          PopulateQuestion(0); //Populate the first question
  }
  private void btnNext_Click(object sender, EventArgs e)
  {
      PopulateQuestion(q + 1);
  }
  private void btnPrev_Click(object sender, EventArgs e)
  {
      PopulateQuestion(q - 1);
  }

[编辑 - 修改代码以使用全局int lastQuest 存储最后一个问题

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