Question

我之前从未做过这样的事情，如果我只传递一个整数就行，但是我有一个我需要用于POSITION_ID的列表。该列表例如仅1,2,3..etc。这会从The specified object must not be an instance of a generic type引发异常ExecuteParameterQuery。我不确定在涉及列表时是否/如何执行此操作。

通过帮助进行的更改。

public List<Dictionary<string, string>> SelectedLineHistory(string partProgram, string machineId, List<int> Line2, bool orderByDate = false)

{
    List<Dictionary<string, string>> results = new List<Dictionary<string, string>>();

    string query = "SELECT MACHINE_ID, PART_PROGRAM, POSITION_ID, DATE_TIME, SAVE_DATE_TIME,DWELL_STIME, ADJUSTED_AMOUNT, DWELL_OFFSET, EMPL_ID " +
                   "FROM MPCS.WJ_DWELL_OFFSETS_HIST " +
                   "WHERE PART_PROGRAM = ? and MACHINE_ID = ? and POSITION_ID = ? ";
    if (orderByDate)
    {
        query += " order by save_date_time desc, position_id asc";
    }

    List<OleDbParameter> queryParameters = new List<OleDbParameter>();

    foreach (var line in Line2)
    {
        queryParameters.Clear();
        queryParameters.Add(new OleDbParameter("PART_PROGRAM", partProgram));
        queryParameters.Add(new OleDbParameter("MACHINE_ID", machineId));
        queryParameters.Add(new OleDbParameter("POSITION_ID", Line));

        results = this.ExecuteParameterQuery(query, queryParameters);
    }
    return (results);
}

如果我不使用results = this.ExecuteParameterQuery(query, queryParameters);代替results.add，我会收到错误，但我不认为这是我的问题。

它仍会产生原始错误The specified object must not be an instance of a generic type

这就是我称之为的方式。在需要使用positionID列表

之前，这又有效

我还在努力弄清楚我要做什么＆＃39;新的＆＃39;正如所建议的那样，但尚未发现它，但希望保持更新。

public void SelectedHistory(bool showMessages = false)
{
    List<Dictionary<string, string>> resultHistory = new List<Dictionary<string, string>>();
    string machineId = cboMachine.Text.Trim().ToUpper();
    string partProg = cboPartPrograms.Text.Trim().ToUpper();

    lvViewHistory.Items.Clear();

    if (!String.IsNullOrEmpty(machineId) && !String.IsNullOrEmpty(partProg))
    {
        resultHistory = oracleConnection.SelectedLineHistory(partProg, machineId, Line2, true);

        if (resultHistory != null && resultHistory.Count > 0)
        {
            foreach (Dictionary<string, string> d in resultHistory)
            {
                ListViewItem lvi = new ListViewItem(d["MACHINE_ID"]);
                lvi.SubItems.Add(d["PART_PROGRAM"]);
                lvi.SubItems.Add(d["POSITION_ID"]);
                lvi.SubItems.Add(d["DATE_TIME"]);
                lvi.SubItems.Add(d["SAVE_DATE_TIME"]);
                lvi.SubItems.Add(d["DWELL_STIME"]);
                lvi.SubItems.Add(d["ADJUSTED_AMOUNT"]);
                lvi.SubItems.Add(d["DWELL_OFFSET"]);
                lvi.SubItems.Add(d["EMPL_ID"]);

                lvViewHistory.Items.Add(lvi);
            }
        }
        else
        {
            MessageBox.Show("No History Found");
        }
    }
    else
    {
        MessageBox.Show("Please select Machine_Id and Part Program");
    }

    lvViewHistory.AutoResizeColumns(ColumnHeaderAutoResizeStyle.HeaderSize);
}

无论出于何种原因它现在都有效，但是不是给我行结果，而是在行2中有很多行号，它只是给我从最后一行号得到的结果。

因此，如果Line2有1,2,3我应该从行号为1 2和3的所有行获得sql结果，而不是我得到行号为3的结果。

Answer 1

我认为您正在寻找以下内容。请注意，它将每个迭代的结果添加到result列表中。它还纠正了@omniowner先前提到的缺陷。

public List<Dictionary<string, string>> SelectedLineHistory(string partProgram, string machineId, List<int> Line2, bool orderByDate = false)
{
    List<Dictionary<string, string>> results;
    string query = "";
    List<OleDbParameter> queryParameters = new List<OleDbParameter>();

    foreach (var line in Line2)
    {
        query = "SELECT MACHINE_ID, PART_PROGRAM, POSITION_ID, DATE_TIME, SAVE_DATE_TIME,DWELL_STIME, ADJUSTED_AMOUNT, DWELL_OFFSET, EMPL_ID ";
        query += "FROM MPCS.WJ_DWELL_OFFSETS_HIST ";
        query += "WHERE PART_PROGRAM = ? and MACHINE_ID = ? and POSITION_ID = ?";

        if (orderByDate)
        {
            query += " order by save_date_time desc, position_id asc";
        }

        queryParameters.Add(new OleDbParameter("PART_PROGRAM", partProgram));
        queryParameters.Add(new OleDbParameter("MACHINE_ID", machineId));

        /* in the following parameter, use this iteration's value, line,  *
         * rather than the entire collection, Line2                       */
        queryParameters.Add(new OleDbParameter("POSITION_ID", line));

        /**** this looks sketchy -- check it *****/
        results.Add(this.ExecuteParameterQuery(query, queryParameters));
    }
    return results;
}

深思熟虑：如上所述，这将为Line2列表中的每个元素执行一次数据库查询/往返。您可能更喜欢只使用where子句执行一个查询，该子句指定Line2中的每个元素。这样会更有效率，但需要更多代码来准备返回此例程调用者的结果。

Answer 2

在我看来，问题是你试图将整个List of Integers作为参数传递给...

queryParameters.Add(new OleDbParameter("POSITION_ID", Line2));

您应该尝试将其更改为您在列表中迭代的项目。像这样......

queryParameters.Add(new OleDbParameter("POSITION_ID", line));

在完成整个列表的迭代之前，您也会返回（正如STLDeveloper在问题评论中提到的那样）。您希望将该return语句移出foreach循环

Answer 3

借用STL +1

public List<Dictionary<string, string>> 
SelectedLineHistory(string partProgram, string machineId, 
                    List<int> Line2, bool orderByDate = false)
{
    List<Dictionary<string, string>> results = new List<Dictionary<string, string>>();

    string query = "SELECT MACHINE_ID, PART_PROGRAM, POSITION_ID, DATE_TIME, SAVE_DATE_TIME,DWELL_STIME, ADJUSTED_AMOUNT, DWELL_OFFSET, EMPL_ID " +
                   "FROM MPCS.WJ_DWELL_OFFSETS_HIST " +
                   "WHERE PART_PROGRAM = ? and MACHINE_ID = ? and POSITION_ID = ? ";
    if (orderByDate)
    {
        query += " order by save_date_time desc, position_id asc";
    }

    List<OleDbParameter> queryParameters = new List<OleDbParameter>();

    foreach (var line in Line2)
    {
        //actually should define parameter outside the loop and just assign the value here
        queryParameters.Clear();
        queryParameters.Add(new OleDbParameter("PART_PROGRAM", partProgram));
        queryParameters.Add(new OleDbParameter("MACHINE_ID", machineId));
        queryParameters.Add(new OleDbParameter("POSITION_ID", Line));

        results.Add(this.ExecuteParameterQuery(query, queryParameters));        
    }
    return (results);
}

Line2是一个List，你还在使用它

queryParameters.Add(new OleDbParameter("POSITION_ID", Line2));

试

queryParameters.Add(new OleDbParameter("POSITION_ID", Line));

SQL Select语句where && 39; List＆＃39 ;?

3 个答案: