菜鸟问题，简单查询，30分。

Question

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        '在此处放置初始化页的用户代码
        Dim objconn As New SqlConnection
        objconn.ConnectionString = "server=localhost;database=northwind;user id=lbright;password="
        objconn.Open()
        Dim objcmd As New SqlCommand
        objcmd.Connection = objconn
        objcmd.CommandText = "select  customerid  as a, employeeid as b from orders"
        Dim objreader As SqlDataReader = objcmd.ExecuteReader()
        Dim i As Integer
        Response.Write("<table border='1'>,<tr align='center'>")
        For i = 0 To objreader.FieldCount - 1
            Response.Write("<td>" & objreader.GetName(i) & "</td>")
        Next
        Response.Write("</tr>")
        While objreader.Read()
            Response.Write("<tr>")
            For i = 0 To objreader.FieldCount - 1
                Response.Write("<td>" & objreader.GetValue(i) & "<td>")            Next
            Response.Write("<tr>")        End While
        Response.Write("</table>")
        objreader.Close()
        objconn.Close()
    End Sub谁知道为什么这段代码运行后怎么在浏览器上没有表格出现么？
在运行过程中也没有抱错。

Answer 1

其中 Response.Write("<td>" & objreader.GetValue(i) & "<td>") 和Response.Write("<tr>") 都已经改成了 Response.Write("<td>" & objreader.GetValue(i) & "</td>")和Response.Write("</tr>") 但是 运行还是不成功。没有表格出来。

Answer 2

重载Render方法，例如： protected override void Render(HtmlTextWriter writer) 
{
//分离字符串
char[] splitChar={';'}; 
string[] resultFieldNames=fieldNameArray.Split(splitChar);
string[] resultErrorMessages=fieldErrorMessageArray.Split(splitChar);
int maxRows=resultFieldNames.Length+1; writer.WriteFullBeginTag("html");
writer.WriteLine(); writer.WriteFullBeginTag("head");
writer.WriteLine();
writer.Write("<link rel=\"stylesheet\" href=\"main.css\">");
writer.WriteLine();
writer.Write("<title>错误信息</title>");
writer.WriteLine();
writer.WriteEndTag("head");
writer.WriteLine(); writer.WriteFullBeginTag("body");
writer.WriteLine(); writer.WriteBeginTag("table border=\"0\" width=\"500\" cellspacing=\"0\" cellpadding=\"0\" style=\"left:10px;POSITION:absolute\"");
writer.Write(HtmlTextWriter.TagRightChar);
writer.WriteLine(); writer.Indent++;
writer.WriteFullBeginTag("tr");
writer.WriteLine();
writer.Indent++;
writer.WriteFullBeginTag("td height=20");
writer.WriteEndTag("td");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine(); writer.WriteFullBeginTag("tr");
writer.WriteLine(); writer.Indent++;
writer.WriteBeginTag("td height=30");
writer.WriteAttribute("align","center");
writer.Write(HtmlTextWriter.TagRightChar);
writer.Write("<font color=\"#FF0000\" size=\"4\"><b>错误信息</b></font>");
writer.WriteEndTag("td");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine(); // ...
writer.WriteFullBeginTag("tr");
writer.WriteLine(); writer.Indent++;
writer.WriteFullBeginTag("td");
writer.WriteLine(); writer.Indent++;
writer.WriteBeginTag("table style=\"border-collapse: collapse\" border=\"1\" width=\"500\" cellspacing=\"0\" cellpadding=\"0\" bordercolor=\"#000080\"");
writer.Write(HtmlTextWriter.TagRightChar);
writer.WriteLine(); writer.Indent++;
for (int i=0; i<maxRows; i++) 
{ writer.WriteFullBeginTag("tr");
writer.WriteLine(); writer.Indent++;
for (int j=0; j<3; j++) 
{
if(j==0)
{
writer.WriteBeginTag("td width=35 height=25");
}
else if(j==1)
{
writer.WriteBeginTag("td width=125 height=25");
}
else if(j==2)
{
writer.WriteBeginTag("td width=340 height=25");
}

writer.WriteAttribute("valign","center");
writer.Write(HtmlTextWriter.TagRightChar);
if(i==0)
{
if(j==0)
{
writer.Write("<p align=\"center\"><b><font color=\"#000000\" size=\"2\">序号</font></b>" );
}
else if(j==1)
{
writer.Write("<p align=\"center\"><b><font color=\"#000000\" size=\"2\">字段名</font></b>" );
}
else if(j==2)
{
writer.Write("<p align=\"center\"><b><font color=\"#000000\" size=\"2\">错误信息</font></b>");
}
}
else
{
if(j==0)
{
writer.Write("<p align=\"center\"><font color=\"#FF0000\" size=\"2\">"+i.ToString()+"</font>" );
}
else if(j==1)
{
writer.Write("<font color=\"#FF0000\" size=\"2\">" + resultFieldNames[i-1] + "</font>" );
}
else if(j==2)
{
writer.Write("<font color=\"#FF0000\" size=\"2\">" + resultErrorMessages[i-1] + "</font>" );
}

}
writer.WriteEndTag("td");
writer.WriteLine();
} writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine();
}
writer.Indent--;
writer.WriteEndTag("table");
writer.WriteLine(); writer.Indent--;
writer.WriteEndTag("td");
writer.WriteLine(); writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine(); writer.WriteFullBeginTag("tr");
writer.WriteLine();
writer.Indent++;
writer.WriteFullBeginTag("td height=20");
writer.WriteEndTag("td");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine();

//加入关闭按钮
writer.WriteFullBeginTag("tr");
writer.WriteLine();
writer.Indent++;
writer.WriteFullBeginTag("td height=25 align=\"center\"");
writer.WriteLine();
writer.Indent++;
writer.Write("<input type=\"submit\" name=\"btnClose\" value=\"关闭\" id=\"btnClose\" class=\"button_all\" style=\"width:60px;height:24px\" onclick=\"javascript:window.close();\"/>");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("td");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine(); writer.WriteFullBeginTag("tr");
writer.WriteLine();
writer.Indent++;
writer.WriteFullBeginTag("td height=20");
writer.WriteEndTag("td");
writer.WriteLine();
writer.Indent--;
writer.WriteEndTag("tr");
writer.WriteLine();
// ...
writer.Indent--;
writer.WriteEndTag("table");
writer.WriteLine(); writer.WriteEndTag("body");
writer.WriteLine(); writer.WriteEndTag("html");
}

Answer 3

写在页面的PreRender事件中....看看！

Answer 4

objreader.GetName(i) 
objreader.GetValue(i)
可能就根本没读出什么数据来。

Answer 5

Response.Write("<table border='1'>,<tr align='center'>")这一句会输出一个",",不知道有没有显示,并且表格就算没有<td>和</td>,也会把表格的边框显示出来.我估计是
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
根本就没有执行.