使用MySQL數據填充ArrayList

我想從數據庫中填充兩個ArrayLists（listOfAnswers和listOfAnswerIDs）字段（'answer'和'answer_id'）。使用MySQL數據填充ArrayList

當字符串cmdText中的question_id = 1時，下面的代碼似乎很好地工作。但是，如果我將其更改爲2或3，則ArrayLists保持空白，我不知道爲什麼。有任何想法嗎？

我認爲這是與字符串作爲cmdGetAnswersQuery 「SELECT * FROM答案WHERE question_id = 2」的作品做...

string connStr = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString; 
    MySqlConnection conn = new MySqlConnection(connStr); 
    MySqlDataReader reader; 

    ArrayList listOfAnswerIDs = new ArrayList(); 
    ArrayList listOfAnswers = new ArrayList(); 
    try 
    { 
     conn.Open(); 
     string cmdText = "SELECT * FROM questions_t WHERE question_id=2"; 
     MySqlCommand cmd = new MySqlCommand(cmdText, conn); 
     cmd.Parameters.Add("@ModuleID", MySqlDbType.Int32); 
     cmd.Parameters["@ModuleID"].Value = ddlModules.SelectedValue; 

     reader = cmd.ExecuteReader(); 

     if (reader.Read()) 
     { 
      lblQuestion.Text = reader["question"].ToString(); 
      ViewState["QuestionID"] = reader["question_id"].ToString(); 
      ViewState["AnswerID"] = reader["correct_answer_id"].ToString(); 

      reader.Close(); 

      string cmdGetAnswersQuery = "SELECT * FROM answers WHERE [email protected]"; 
      MySqlCommand cmdGetAnswers = new MySqlCommand(cmdGetAnswersQuery, conn); 
      cmdGetAnswers.Parameters.Add("@QuestionID", MySqlDbType.Int32); 
      cmdGetAnswers.Parameters["@QuestionID"].Value = ViewState["AnswerID"]; 

      reader = cmdGetAnswers.ExecuteReader(); 

      while (reader.Read()) 
      { 
       listOfAnswerIDs.Add(reader["answer_id"].ToString()); 
       listOfAnswers.Add(reader["answer"].ToString()); 
      } 
      reader.Close(); 
      populateAnswers(listOfAnswers, listOfAnswerIDs); 
     } 
     else 
     { 
      reader.Close(); 
      lblError.Text = "(no questions found)"; 
     } 
    } 
    catch 
    { 
     lblError.Text = "Database connection error - failed to insert record."; 
    } 
    finally 
    { 
     conn.Close(); 
    }

實際的數據庫內容如下所示： http://i.imgur.com/3S4lV60.png http://i.imgur.com/8A913xF.png

來源

2014-07-09 Bhav

嗯，我討厭問這個問題，但是......甚至有'question_id = 2'或'question_id = 3'的行嗎？ – Jashaszun

@Jashaszun是啊 - http://imgur.com/8A913xF，http://imgur.com/3S4lV60 – Bhav

年2k14，我們仍然使用'ArrayList'編碼？ –

我不能肯定地說這是問題，但我要看的第一件事是這行代碼：

cmdGetAnswers.Parameters["@QuestionID"].Value = ViewState["AnswerID"];

我懷疑你想要那ViewState["QuestionID"]。

來源

2014-07-09 19:02:10

使用MySQL數據填充ArrayList

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