我在做什么？ pdfptable构造函数中的列数必须大于零 [英] What I mising? The number of columns in pdfptable constructor must be greater than zero

问题描述

The number of columns in PdfPTable constructor must be greater than zero

我有什么试过：

What I have tried:

<pre>

private static DataTable dt = new DataTable();
/////////////////////////////////////////////////////////


private static void slanjeizvestaja()
        {
            String cs = "Data Source=.\\SQLEXPRESS;Initial Catalog=bss_prijava_radnika;Integrated Security=True";
            using (SqlConnection openCon = new SqlConnection(cs))

            {

                string pronadji = "SELECT p.brojprijavnice2 AS Redni_broj, p.radnik AS Radnik, p.vrijemeprijave AS Vrijeme_Prijave, p.vrijemeodjave AS Vrijeme_odjave"
                                 + " FROM dbo.prijava_radnika p WHERE p.status = 'odjavljen'";



                openCon.Open();
                using (SqlDataAdapter querySaveStaff = new SqlDataAdapter(pronadji, cs))

                {
                    DataTable dt = new DataTable();
                    querySaveStaff.Fill(dt);
                }
                openCon.Close();
            }
        }

        private static void sendEmail()
        {


            PdfPTable pdfTable = new PdfPTable(dt.Columns.Count);
            pdfTable.DefaultCell.Padding = 3;
            pdfTable.WidthPercentage = 100;
            pdfTable.HorizontalAlignment = Element.ALIGN_LEFT;
            pdfTable.DefaultCell.BorderWidth = 1;
            BaseFont bfCalibri = BaseFont.CreateFont("c:\\windows\\fonts\\calibri.ttf", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
            iTextSharp.text.Font calibri = new iTextSharp.text.Font(bfCalibri, 12);

推荐答案

您的 slanjeizvestaja 声明一个名为 dt 的新变量，它掩盖了 sendEmail 用于其数据：



Your slanjeizvestaja declares a new variable called dt which masks the private static version that sendEmail is using for its data:

using (SqlDataAdapter querySaveStaff = new SqlDataAdapter(pronadji, cs))

{
    DataTable dt = new DataTable();
    querySaveStaff.Fill(dt);

不管怎样，你的数据会在方法结束时被丢弃。

尝试：

Becasue of that, your data is thrown away at the end of the method.
Try:

using (SqlDataAdapter querySaveStaff = new SqlDataAdapter(pronadji, cs))

{
    dt = new DataTable();
    querySaveStaff.Fill(dt);

看看是否修复了它。

这里的dt

The "dt" in here

{
    DataTable dt = new DataTable();
    querySaveStaff.Fill(dt);
}

只存在于该代码块中（{}之间），所以你创建了dt，填充它，然后扔掉它。所以这里的代码是这样的;

Only exists in that code block (between the { } ), so you create dt, populate it, then throw it away. So this code here;

PdfPTable pdfTable = new PdfPTable(dt.Columns.Count);

使用此处定义的dt

is using the "dt" defined here

private static DataTable dt = new DataTable();

该dt保持不变，因此零列没有数据。更改slanjeizvestaja中的代码以使用顶部定义的dt而不是创建第二个dt

That dt remains untouched so has zero columns and no data. Change the code in slanjeizvestaja to use the dt defined at the top rather than creating a second "dt"

{
    dt = new DataTable();
    querySaveStaff.Fill(dt);
}

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