c# - 错误 : No value given for one or more required parameters

Question

我正在尝试通过比较 dataetimepicker 的 month and year value 与存储在 Date/Time 类型的数据库列中的日期来获取 Id，如下是我用来执行此操作的查询，但它在这一行显示以下错误 while (rs.Read())

错误

No value given for one or more required parameters.

代码

public int GetDrID_MonthWise(string DrName,int month,int year, int refDrID)
{
    int data = 0;
    try
    {
        string sql = "Select d.DoctorID From Doctor_Master d,Patient_registration p where d.LastName + ' ' + d.FirstName = '" + DrName + "' AND datepart(mm,p.[RegDate])=@month AND datepart(yyyy,p.[RegDate])=@year AND p.DoctorID=" + refDrID;
        cmd = new OleDbCommand(sql, acccon);
        cmd.Parameters.AddWithValue("@month", month);
        cmd.Parameters.AddWithValue("@year", year);
        rs = cmd.ExecuteReader();
        while (rs.Read())
        {
            data = Convert.ToInt32(rs[0]);
        }
    }
    catch (Exception err)
    {
        MessageBox.Show(err.Message.ToString());
    }
    return data;
}

我像这样传递月份和年份值，我在哪里做错了？

int month = dateTimePickerMonth.Value.Month;
int year = dateTimePickerMonth.Value.Year;

Answer 1

您的查询有误，请按此操作，

 string sql = "Select d.DoctorID From Doctor_Master d,Patient_registration p where d.LastName + ' ' + d.FirstName = '" + DrName + "' AND datepart("m",p.[RegDate])=@month AND datepart("yyyy",p.[RegDate])=@year AND p.DoctorID=" + refDrID;

注意:您必须在 ms Access 的 DatePart 函数中用 ""括起日期间隔，并且只能用单个 m 表示月份。如果您没有用“”括起yyyy和m，系统认为yyyy和m是参数和这些参数的期望值。

If you execute your query in Ms-Aceess sql view then it will show thismessage "Enter Paremeter Value".