Question

我尝试从我的c＃project中的2个数据库表中检索一些数据，即AnswersTable和QuestionsTable。AnswerTtable包含名为＆＃34; QuestionID＆＃34;和＆＃34; UserId＆＃34;我试图查询用户使用UserID和QuestionID尝试的每个问题。如果用户尝试了10个问题，并且每个问题都有唯一ID，我将如何使用QuestionID查询用户尝试的所有问题。这就是我从AnswersTable

中检索questionId的方法

String questionid;
Query = "SELECT * FROM AnswersTable WHERE UserId = '1'";
           theReader = conn.ExecuteStatement(Query);
           while (theReader.Read())
           {


               questionid = theReader["QuestionId"].ToString();

           }

在检索或读取questionID后，我将其传递给下一个查询：

Query = "SELECT *  FROM QuestionsTable WHERE Id = '" + questionid + "'";
            theReader = conn.ExecuteStatement(Query);
            while(theReader.Read())
            {

              // I know I meant to do something in here in order to retrieve all the 10 attempted 
               //questions using their Unique IDs, how do I retrieve each and every question using 
               // the questionIDs?

            }

我希望这是有道理的，谢谢

Answer 1

您可以通过加入两个表，使用以下查询获取特定用户（在本例中为用户ID = 1）的所有问题及其答案。这样您就不需要拥有两个数据读取器。希望这会有所帮助。

SELECT A.AnswerId      
      ,A.UserID
       ,A.QuestionId
      ,Q.Question
      ,A.Answer
FROM AnswersTable A
    INNER JOIN QuestionsTable Q ON Q.QuestionId = A.QuestionId
WHERE UserID = 1

使用唯一ID从两个表中读取数据

1 个答案: