Question

我在用c＃编写的WPF应用程序中遇到以下问题。我需要在sql server上创建一些临时表，从app中进行一些连接，然后从连接表中选择。在统计语言R中，我只创建两个SQL查询（一个包含#tables，另一个包含来自几个#tables的合并的最终select语句）并一个接一个地执行它们。仅在一个Query中执行查询仅在创建#temp表后返回NULL。

这是SQL语句＃1：

DECLARE @from_time Date;
DECLARE @to_time Date;

CREATE TABLE #temp1
     (
person_id float,
first_name varchar(100),
othercols...
) 


INSERT INTO #temp1
SELECT DISTINCT
   person_id, first_name, ...
FROM
campus.v_exam_registration_context context
FULL JOIN
campus.v_exam_timetable time
ON
CAST(context.examination_date AS DATETIME) = time.timetable_date
AND
context.examination_time_from = time.time_from
AND
context.examination_time_to = time.time_to  

CREATE TABLE #temp2
(
exam_event_id float,
person_id float, 
othercols...
)  


INSERT INTO #temp2
SELECT DISTINCT
exam_event_id, person_id, excused, excused_reason, missed, modify_date, study_id, study_name,
person_exam_id, exam_in_course_id, subject, subject_unicode, personal_exam_no, exam_points, grade_description
FROM
campus.v_person_exam exam
WHERE
exam.person_id
IN
(
SELECT
  #temp1.person_id
  FROM
    #temp1
  WHERE
    #temp1.attempt_counter > 1
  AND
    #temp1.timetable_date > @from_time 
  AND
    #temp1.timetable_date < @to_time
  )  

  CREATE TABLE #temp3
  (
  person_id float,
  first_name varchar(100),
) 

INSERT INTO #temp3
SELECT 
#temp2.person_id, first_name, last_name, matriculation_number, attempt_counter, timetable_date, examination_date, semester, course_number, course_name, 
exam_name, exam_type, component_name, course_area, module_number, module_name, credits, 
FROM 
#temp2
LEFT JOIN 
#temp1
ON
#temp2.person_id = #temp1.person_id
AND
#temp2.exam_event_id = #temp1.exam_event_id
WHERE
#temp1.course_name IS NOT NULL

这是＃2：

SELECT DISTINCT T1.* 
FROM 
#temp3 T1
INNER JOIN  
(
 SELECT * 
 FROM 
    #temp3  
 WHERE 
    #temp3.attempt_counter > 1
 AND
    #temp3.exam_points > 4
 AND
    #temp3.timetable_date > @from_time
 AND
    #temp3.timetable_date < @from_time
 ) as T2
 ON
  T1.person_id = T2.person_id
 AND 
  T1.exam_name = T2.exam_name
 ORDER BY T1.last_name ASC, T1.course_name DESC, T1.timetable_date ASC

但现在我需要将R脚本翻译成一个独立的exe文件。这是我在c＃中的代码块：

    private void queryButton_Click(object sender, RoutedEventArgs e)

    {

        List<Student> temp = new List<Student>();
        string pass = @pass_box.Password;
        string dsn = "CampusNet";
        String ConnectionString =
            "DSN=" + dsn + ";" +
            "UID=" + uid + ";" +
            "PWD=" + pass;

        OdbcConnection conn = new OdbcConnection(ConnectionString);
        using (conn)
        {
            if (conn.State.ToString() == "Open")
            {
                conn.Close();
            }
            try
            {
                conn.Open();

                var command = new OdbcCommand(sqlcommand, conn); \\sqlcommand is read from a textfile
                command.Parameters.AddWithValue("@from_time", from_time);
                command.Parameters.AddWithValue("@to_time", to_time);
                command.CommandTimeout = 120;
                var resultCommand = command.ExecuteNonQuery(); 

                var query = new OdbcCommand(sqlquery, conn); \\sqlquery is read from a textfile
                query.Parameters.AddWithValue("@from_time", from_time);
                query.Parameters.AddWithValue("@to_time", to_time);
                var resultQuery = query.ExecuteReader();

                Results_Box.AppendText(resultQuery.HasRows.ToString());
                while (resultQuery.Read())
                {  
        temp.Add(new Student{
            name = !result.IsDBNull(3) ? result.GetString(3) : null
        });
                    Results_Box.AppendText("Test"); \\only for testing purposes, works if I select from existing table
                }
                resultQuery.Close();
                results = temp;

                Results_Box.Document.Blocks.Add(new Paragraph(
                    new Run("There are " + temp.Count().ToString() + " Hits")));   
                System.Windows.Forms.MessageBox.Show("Connected");
                conn.Close();
            }
            catch (Exception E)
            {
                Results_Box.Document.Blocks.Add(new Paragraph(new Run("Connection failed")));
                Results_Box.Document.Blocks.Add(new Paragraph(new Run(E.ToString())));
            }

        }
    }

我是c＃的新手，所以似乎第一个查询被执行但之后立即被删除而第二个select语句返回0次点击。如果我从非临时表中选择一切正常。由于第一个查询的持续时间大约等于相应的R-Query（25秒），我怀疑第一个查询是否正确执行，但是在第一个查询完成之前立即删除或第二个查询开始。创建一个组合查询在R和c＃中都不起作用。我想坚持使用临时表，而不是使用##表，如果可能的话。

是否有一种特殊的方法可用于在c＃中创建临时表？ conn.open()在using (conn){...}

的整个运行时间内处于打开状态

创建一个临时表，然后选择

0 个答案: