为何记录不动 [英] Why records not moving

问题描述

我的数据库中的两条记录。当我点击下一步按钮然后发出一条错误消息

位置1没有行

i我正在使用下面的代码。

任何人请帮助我在代码中出错的地方。

Two records in my database.when i click on next button then one error message coming
"There is no row at position 1"
i am using below code .
anyone please help me where i am doing mistake in code.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace MyProject
{

    public partial class Form1 : Form
    {
        int i = 0;
        
        public Form1()
        {
            InitializeComponent();
        }

       private void Form1_Load(object sender, EventArgs e)
        {
           SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\manish\Documents\HRM.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
            conn.Open();
            SqlCommand command = new SqlCommand("select * from emp_detail", conn);
            SqlDataAdapter adp = new SqlDataAdapter(command);
            DataTable tbl = new DataTable();
            adp.Fill(tbl);
            display(tbl);
       }
           private void display(DataTable tbl)
           {
           txtempid.Text = tbl.Rows[i][0].ToString();
            txtname.Text = tbl.Rows[i][1].ToString();
            txtsurname.Text = tbl.Rows[i][2].ToString();
            txtfathername.Text = tbl.Rows[i][3].ToString();
            dtdob.Text = tbl.Rows[i][4].ToString();
            cbgender.Text = tbl.Rows[i][5].ToString();
            cbcity.Text = tbl.Rows[i][6].ToString();
            txtcontactno.Text = tbl.Rows[i][7].ToString();
            dtdoj.Text = tbl.Rows[i][8].ToString();
            txtdept.Text = tbl.Rows[i][9].ToString();
            txtdesig.Text = tbl.Rows[i][10].ToString();
            txtqualification.Text = tbl.Rows[i][11].ToString();
            rtaddress.Text = tbl.Rows[i][12].ToString();
            rtremarks.Text = tbl.Rows[i][13].ToString();
            
        }
           private void button8_Click(object sender, EventArgs e)
           {
               DataTable tbl = new DataTable();

               if (i > tbl.Rows.Count - 1)
               {
                   i++;

                   display(tbl);
               }
               else
               {
                   MessageBox.Show("this is last records");
               }
           }

推荐答案

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
 
namespace MyProject
{
 
    public partial class Form1 : Form
    {
        int i = 0;
        DataTable tbl = new DataTable();
        public Form1()
        {
            InitializeComponent();
        }
 
    private void Form1_Load(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\manish\Documents\HRM.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
        conn.Open();
        SqlCommand command = new SqlCommand("select * from emp_detail", conn);
        SqlDataAdapter adp = new SqlDataAdapter(command);
        //DataTable tbl = new DataTable();
        adp.Fill(tbl);
        display(tbl);
    }
    private void display(DataTable tbl)
    {
        txtempid.Text = tbl.Rows[i][0].ToString();
        txtname.Text = tbl.Rows[i][1].ToString();
        txtsurname.Text = tbl.Rows[i][2].ToString();
        txtfathername.Text = tbl.Rows[i][3].ToString();
        dtdob.Text = tbl.Rows[i][4].ToString();
        cbgender.Text = tbl.Rows[i][5].ToString();
        cbcity.Text = tbl.Rows[i][6].ToString();
        txtcontactno.Text = tbl.Rows[i][7].ToString();
        dtdoj.Text = tbl.Rows[i][8].ToString();
        txtdept.Text = tbl.Rows[i][9].ToString();
        txtdesig.Text = tbl.Rows[i][10].ToString();
        txtqualification.Text = tbl.Rows[i][11].ToString();
        rtaddress.Text = tbl.Rows[i][12].ToString();
        rtremarks.Text = tbl.Rows[i][13].ToString();
    }
    private void button8_Click(object sender, EventArgs e)
    {
        //DataTable tbl = new DataTable();
 
        if (i <=tbl.Rows.Count)
        {
        i++;
 
        display(tbl);
    }
    else
    {
        MessageBox.Show("this is last records");
    }
}

继Jawad Ahmed Tanoli的解决方案...



问题的原因是可变范围 [ ^ ]



DataTable tbl 与Button8_Click事件中的 tbl 不同！



Jawad的代码所做的是将DataTable tbl的声明移动到 Form 级别范围，因此同一个实例（即在Form_Load中加载的数据）可用于此Form类中的所有函数。

Further to Jawad Ahmed Tanoli's solution...

The cause of your problem is Variable Scope[^]

The DataTable tbl is not the same as the tbl in your Button8_Click event!

What Jawad's code does is move the declaration of DataTable tbl to Form level scope, so the same instance (i.e. the data that is loaded at Form_Load) is available to all the functions within this Form class.

private void button8_Click(object sender, EventArgs e)
          {
              DataTable tbl = new DataTable();
//this datatable tbl is not filled here with data
              if (i > tbl.Rows.Count - 1)
              {
                  i++;

                  display(tbl);
              }
              else
              {
                  MessageBox.Show("this is last records");
              }
          }

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