使用C#打印文档从SqlServer数据库打印多页

Question

我有一个数据库表，其中有300多条记录，我想使用PrintDocument/PrintPreview打印它，但问题是只有一页显示在PrintPreview中，其余记录丢失了。下面是我的代码，请帮我。

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
int valueYPos=80;
int valueXPos=20
string classId=1;
con.SqlQuery("select [RollNo],[Name] from [dbo].[StudentRegistration] where [ClassId]='" 
+ classId + "'");
con.ExQuery();
foreach (DataRow item in con.ExQuery().Rows)
{
e.Graphics.DrawString("RollNo" +item[0].ToString(), new Font("Arial", 20, 
FontStyle.Bold), Brushes.Black, new Point(valueXPos, valueYPos));
e.Graphics.DrawString("RollNo" +item[1].ToString(), new Font("Arial", 20, 
FontStyle.Bold), Brushes.Black, new Point(valueXPos+20, valueYPos));
valueYPos +=20;
}
}
private void button1_Click(object sender, EventArgs e)
{
PrintPreviewDialog pPD = new PrintPreviewDialog();
pPD.Document = printDocument1;
pPD.ShowDialog();
}

Answer 1

我不会尝试在PrintPage事件中执行这样的查询。将查询的执行移动到BeginPrint事件中，并在EndPrint事件中执行清理。使用SqlDataReader，您可以在PrintPage处理程序中引用和迭代它。类似这样的代码，尽管您显然需要处理页眉、页脚、页边距、列等。如果用户单击PrintPreviewDialog中的打印按钮，此代码也将正确地重新执行查询。

private SqlConnection conn;
private SqlCommand cmd;
private SqlDataReader reader;
private void button1_Click(object sender, EventArgs e)
{
PrintDocument pDoc = new PrintDocument();
pDoc.BeginPrint += new PrintEventHandler(this.BeginPrint);
pDoc.EndPrint += new PrintEventHandler(this.EndPrint);
pDoc.PrintPage += new PrintPageEventHandler(this.PrintPage);

PrintPreviewDialog pPD = new PrintPreviewDialog();
pPD.Document = pDoc;
pPD.ShowDialog();
}
private void BeginPrint(object sender, PrintEventArgs e)
{
const string sql = "SELECT [Name] FROM [StudentRegistration]";
SqlConnection conn = new SqlConnection(ConnStr);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
conn.Open();
reader = cmd.ExecuteReader(CommandBehavior.SingleResult);
}   
private void EndPrint(object sender, PrintEventArgs e)
{
reader.Close();
cmd.Dispose();
conn.Dispose(); 
}
private void PrintPage(object sender, PrintPageEventArgs e)
{
Font myFont = new Font("Arial", 20, FontStyle.Bold);
int rowHt = myFont.Height();
int valueYPos = 80;
int valueXPos = 20;

bool pageDone = false;
bool moreData = false;
while (!pageDone)
{
moreData = reader.Read();
pageDone = !moreData;
if (moreData)
{
e.Graphics.DrawString(reader.GetString(0), myFont, Brushes.Black, valueXPos, valueYPos);
valueYPos += rowHt;

// Is there room to print another row on this page?
if (valueYPos + rowHt > (e.PageBounds.Height))
pageDone = true;
}
}
e.HasMorePages = moreData;
}

Answer 2

有关打印预览对话框，请参阅以下答案在C#中显示打印预览

首先，你不能访问这样的数据，因为当它试图打印每一页时，它会试图访问数据。

private int pageNo = 1;
private static void Print_Invoice(object sender, PrintPageEventArgs e)
{
int valueYPos=80;
int valueXPos=20
string classId=1;
con.SqlQuery("select [RollNo],[Name] from [dbo].[StudentRegistration] where [ClassId]='"+ classId + "'");
con.ExQuery();
switch (pageNo)
{
case 1:
//Print some Data
e.HasMorePages = true;
break;
case 2:
//Print some Data
e.HasMorePages = true;
break;
case 3:
//Print some Data
e.HasMorePages = false;
break;
default:
e.HasMorePages = false;
break;
}
pageNo++;

}

希望能解决你的问题