变量和方法

发布于 2024-11-25 05:10:15 字数 879 浏览 1 评论 0原文

我试图更好地理解如何声明变量（字符串）以及方法如何工作。我正在尝试将日期（从日历扩展程序）重新格式化为字符串，并将其作为参数传递到填充网格视图的查询中。（这与我的上一个问题有关。）转换语句如下所示：

string s_apptdate = apptDate_CalendarExtender.SelectedDate.ToString("yyyyMMdd");

应该放在下面的方法中吗？或者以它自己的方式？当我将其放入下面的方法中时，出现错误“方法‘ToString’没有重载需要 1 个参数” 我的方法看起来像这样

private void query1() 
{
    string s_apptdate = "07/15/2011";
    SqlConnection conn = new SqlConnection("Data Source=*****;Initial Catalog=*****;Persist Security Info=True;User ID=sa;Password=*****");
    string command = "SELECT column1, column2 FROM table where appt_date = '" + s_apptdate + "'";
    SqlDataAdapter comm = new SqlDataAdapter(command, conn);
    DataSet ds = new DataSet();
    comm.Fill(ds);
    GridView1.DataSource = ds;
    GridView1.DataBind();
}

原文

I'm trying to understand better how to declare a variable (string) and how methods work. I'm trying to reformat a date (from a calendarextender) into a string and pass it as a parameter into a query that populates a gridview. (This is related to my previous question.)
The converting statement looks like this:

string s_apptdate = apptDate_CalendarExtender.SelectedDate.ToString("yyyyMMdd");

Should it go in the method below? Or in a method all it's own? When I put it in the method below, I get an error "No overload for method 'ToString' takes 1 arguments"
My method looks like this

private void query1() 
{
    string s_apptdate = "07/15/2011";
    SqlConnection conn = new SqlConnection("Data Source=*****;Initial Catalog=*****;Persist Security Info=True;User ID=sa;Password=*****");
    string command = "SELECT column1, column2 FROM table where appt_date = '" + s_apptdate + "'";
    SqlDataAdapter comm = new SqlDataAdapter(command, conn);
    DataSet ds = new DataSet();
    comm.Fill(ds);
    GridView1.DataSource = ds;
    GridView1.DataBind();
}

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娇纵 2024-12-02 05:10:15

您的 SelectedDate 属性可能是 DateTime? （或 Nullable），在这种情况下，您必须

apptDate_CalendarExtender.SelectedDate.Value.ToString("yyyyMMdd");

在检查 SelectedDate 是否有值后执行此操作

string s_apptdate;
if (apptDate_CalendarExtender.SelectedDate.HasValue)
  s_apptdate = apptDate_CalendarExtender.SelectedDate.Value.ToString("yyyyMMdd");
else
  s_apptdate = string.Empty;

Your SelectedDate property is probably a DateTime? (or Nullable<DateTime>) in wich case you have to do

apptDate_CalendarExtender.SelectedDate.Value.ToString("yyyyMMdd");

after checking if SelectedDate has a value

string s_apptdate;
if (apptDate_CalendarExtender.SelectedDate.HasValue)
  s_apptdate = apptDate_CalendarExtender.SelectedDate.Value.ToString("yyyyMMdd");
else
  s_apptdate = string.Empty;

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