在c＃中复制记录

Question

I am making a attendance system, and here is my problem now, after i searched for a name of a person and try to log him in for attendance, it is fine at first, after logging in the second name it is still fine. but once i tried to edit the login attendance of the first or second user, all the values in my datagridview(connected to my database) became duplicated. if i enter name1 for attendance in my week1 it is fine. name2 for attendance in week1 is still fine. but if i edit the same name. or even go to the next week number, all of the saved values got duplicated based on my recent inputed name. for inserting new records

    SqlConnection cnn200 = new SqlConnection(connectionstring);
            string sql200 = "SELECT * FROM attendance WHERE csign=@csign ";
            cnn200.Open();
            SqlCommand cmd200 = new SqlCommand(sql200, cnn200);
            SqlDataReader rdr200;
            cmd200.Parameters.AddWithValue("@csign", callsign);

            rdr200 = cmd200.ExecuteReader();

                if (rdr200.Read() == true)

                {
            SqlConnection cnn201 = new SqlConnection(connectionstring);
                    if (textBox89.Text == "1")
                    {
                        string sql201 = "insert INTO attendance  
           (csign,name,week1)" + "VALUES" + "(@csign,@name,@week1)";
                        cnn201.Open();
                        SqlCommand cmd201 = new SqlCommand(sql201, cnn201);
                        cmd201.Parameters.AddWithValue("@csign", callsign); 
       cmd201.Parameters.AddWithValue("@name", namee);
                        cmd201.Parameters.AddWithValue("@week1", 
          comboBox1.Text);

                        cmd201.ExecuteNonQuery();
                    }
                if (textBox89.Text == "2")
                {
                    string sql201 = "insert INTO attendance  
              (csign,name,week2)" + "VALUES" + "(@csign,@name,@week2)";
                    cnn201.Open();
                    SqlCommand cmd201 = new SqlCommand(sql201, cnn201);
                    cmd201.Parameters.AddWithValue("@csign", callsign); 
           cmd201.Parameters.AddWithValue("@name", namee);
                    cmd201.Parameters.AddWithValue("@week2", 
              comboBox1.Text);

                    cmd201.ExecuteNonQuery();
                }

and for updating

             else{
             SqlConnection cnn201 = new SqlConnection(connectionstring);
                    if (textBox89.Text == "1")
                    {
                        string sql201 = "UPDATE attendance SET 
          name=@name,csign=@csign,week1=@week1";
                        cnn201.Open();
                        SqlCommand cmd201 = new SqlCommand(sql201, cnn201);

                       cmd201.Parameters.AddWithValue("@name", namee);   
                  cmd201.Parameters.AddWithValue("@csign", callsign);
                        cmd201.Parameters.AddWithValue("@week1", 
                    comboBox1.Text);

                        cmd201.ExecuteNonQuery();
                    }
                if (textBox89.Text == "2")
                {
                    string sql201 = "UPDATE attendance SET 
                   name=@name,csign=@csign,week2=@week2";
                    cnn201.Open();
                    SqlCommand cmd201 = new SqlCommand(sql201, cnn201);

                    cmd201.Parameters.AddWithValue("@name", namee); 
                     cmd201.Parameters.AddWithValue("@csign", callsign);
                    cmd201.Parameters.AddWithValue("@week2", 
                    comboBox1.Text);

                    cmd201.ExecuteNonQuery();
                }`}

Answer 1

nica, I think I can help. What you are trying to do can be done easily with less coding lines. An entire DataGridView can be displayed, edited, deleted and have no duplicates by using a few more objects

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.Globalization;
using System.Data.SqlClient;
using System.IO;
using System.Configuration;


namespace ADO_NET_Testbed
{
    public partial class MainForm : Form
    {
        private SqlDataAdapter adapter;
        private string connectionString = @"Data Source=Server;Persist Security Info=True;Password=password!;User ID=sooperuser;Initial Catalog=Database";
        private string sqlcommand = @"SELECT OPID, LastName, FirstName, Title, PhoneOffice, PhoneCell, Email, Active, Admin, Tester, Educator, Developer FROM AuditUser";
        private SqlCommandBuilder cmdBuilder = new SqlCommandBuilder();
        private DataTable datatable = new DataTable();
        private DataSet dataset = new DataSet();

        public MainForm()
        {
            InitializeComponent();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            adapter = new SqlDataAdapter(sqlcommand, connectionString);
            adapter.Fill(dataset, "AuditUser");
            dgvUsers.DataSource = dataset.Tables[0];
            dgvUsers.Enabled = true;
            this.Show();
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            dataset.Clear();
            dataset.Reset();
            this.Close();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            cmdBuilder.DataAdapter = adapter;
            adapter.Update(dataset.Tables[0]);
            this.Close();
        }
    }
}

As a quick rundown of what is going on, the SqlDataAdapter holds the four queries, but auto-creates three from the SELECT command. Using a SqlCommandBuilder enables the other three to be added, although the debugger will not show them as anything but NULL. The adapter.Fill() and adapter.Update() handle all the different commands based on the RowState of each row in the datagridview. "Cancel" is overkill seeing as this form is closed anyway.