请问我的这段代码有什么错呀?运行的时候说:未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。//获取连接字符串
string connectionString = ConfigurationManager.ConnectionStrings["ttConnectionString"].ConnectionString;
//创建并设置SqlConnection
SqlConnection dbConnection = new SqlConnection(connectionString);
//定义SQL查询语句
string queryString = "Select * from text";
//创建并设置SqlCommand
SqlCommand dbCommand = new SqlCommand();
dbCommand.Connection = dbConnection;
dbCommand.CommandType = CommandType.Text;
dbCommand.CommandText = queryString;
//创建SqlDataAdapter,并获取数据
SqlDataAdapter dataAdapter = new SqlDataAdapter(dbCommand);
DataSet ds = new DataSet();
dataAdapter.Fill(ds);
PagedDataSource objds = new PagedDataSource();
objds.DataSource = ds.Tables["text"].DefaultView;//dataset 数据源
objds.AllowPaging = true;
objds.PageSize = 6;
DataList1.DataSource = objds;
DataList1.DataBind();
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。//获取连接字符串
string connectionString = ConfigurationManager.ConnectionStrings["ttConnectionString"].ConnectionString;
//创建并设置SqlConnection
SqlConnection dbConnection = new SqlConnection(connectionString);
//定义SQL查询语句
string queryString = "Select * from text";
//创建并设置SqlCommand
SqlCommand dbCommand = new SqlCommand();
dbCommand.Connection = dbConnection;
dbCommand.CommandType = CommandType.Text;
dbCommand.CommandText = queryString;
//创建SqlDataAdapter,并获取数据
SqlDataAdapter dataAdapter = new SqlDataAdapter(dbCommand);
DataSet ds = new DataSet();
dataAdapter.Fill(ds);
PagedDataSource objds = new PagedDataSource();
objds.DataSource = ds.Tables["text"].DefaultView;//dataset 数据源
objds.AllowPaging = true;
objds.PageSize = 6;
DataList1.DataSource = objds;
DataList1.DataBind();
解决方案 »
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再定义四个LinkButton控件,ID分别为“lnkbtnTop”、“lnkbtnPrve”、“lnkbtnNext”和“lnkbtnLast”,分别用来进行“首页”、“上一页”、“下一页”和“尾页”的翻页操作。
当然还有一个DataList(ID="DataList1")控件了。//cs文件中的内容
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
dlBind();
}
}
public void dlBind()
{
int curpage = Convert.ToInt32(labNowPage.Text);
PagedDataSource ps = new PagedDataSource();
SqlConnection myCnn = new SqlConnection("server=(local);uid=sa;pwd=sa;database=pubs");
myCnn.Open();
SqlDataAdapter myAdp = new SqlDataAdapter("select * from authors", myCnn);
DataSet ds = new DataSet();
myAdp.Fill(ds, "authors"); ps.DataSource = ds.Tables["authors"].DefaultView;
ps.AllowPaging = true;
ps.PageSize = 4;
ps.CurrentPageIndex = curpage - 1; lnkbtnPrve.Enabled = true;
lnkbtnTop.Enabled = true;
lnkbtnNext.Enabled = true;
lnkbtnLast.Enabled = true;
if (curpage == 1)
{
lnkbtnTop.Enabled = false;
lnkbtnPrve.Enabled = false;
}
if (curpage == ps.PageCount)
{
lnkbtnNext.Enabled = false;
lnkbtnLast.Enabled = false;
}
labCount.Text = Convert.ToString(ps.PageCount);
DataList1.DataSource = ps;
DataList1.DataKeyField = "au_id";
DataList1.DataBind();
}
protected void lnkbtnPrve_Click(object sender, EventArgs e)
{
labNowPage.Text = Convert.ToString(Convert.ToInt32(labNowPage.Text) - 1);
dlBind();
}
protected void lnkbtnTop_Click(object sender, EventArgs e)
{
labNowPage.Text = "1";
dlBind();
}
protected void lnkbtnNext_Click(object sender, EventArgs e)
{
labNowPage.Text = Convert.ToString(Convert.ToInt32(labNowPage.Text) + 1);
dlBind();
}
protected void lnkbtnLast_Click(object sender, EventArgs e)
{
labNowPage.Text = labCount.Text;
dlBind();
}
create procedure wzl
(@startIndex int,
@pageSize int)
as
set nocount on
declare @MyTable table(id int identity(1,1),nid int);
declare @PageUpperBound int;
set @PageUpperBound=@startIndex+@pagesize-1;
set rowcount @PageUpperBound;
insert into @MyTable(nid) select orderid from orders;
select * from @MyTable as x left outer join orders on orders.orderid = x.id
where x.id between @startIndex and @PageUpperBound
set nocount off
RETURN用哪个AspNetPager页面代码
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Security;
using System.Text.RegularExpressions;
using System.Data.SqlClient;
namespace Test
{public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataList DataList1;
protected Wuqi.Webdiyer.AspNetPager AspNetPager1;private void Page_Load(object sender, System.EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;pwd=sa;uid=sa;database=northwind");
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.Text;
cmd.Connection = conn;
cmd.CommandText = "select count(orderid) from orders";
conn.Open();
this.AspNetPager1.RecordCount = (int)cmd.ExecuteScalar();
conn.Close();
bindData();
}
void bindData()
{
SqlConnection conn = new SqlConnection("server=.;pwd=sa;uid=sa;database=northwind");
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.StoredProcedure;
cmd.Connection = conn;
cmd.CommandText = "wzl";
cmd.Parameters.Add("@startIndex",this.AspNetPager1.StartRecordIndex);
cmd.Parameters.Add("@pageSize",this.AspNetPager1.PageSize);
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
sda.Fill(ds);
this.DataList1.DataSource = ds.Tables[0].DefaultView;//DataList1.DataSource = SqlHelper.ExecuteReader(CommandType.StoredProcedure,"P_GetPagedOrders2000",
//new SqlParameter("@startIndex", AspNetPager1.StartRecordIndex),
//new SqlParameter("@pageSize", AspNetPager1.PageSize));
this.DataList1.DataBind();
}#region Web 窗体设计器生成的代码
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.AspNetPager1.PageChanged += new System.EventHandler(this.AspNetPager1_PageChanged);
this.Load += new System.EventHandler(this.Page_Load);}
#endregionprivate void AspNetPager1_PageChanged(object sender, System.EventArgs e)
{
bindData();
}}
}