c# - 如何在 C# 中保存此表？

Question

我在数据库中保存表时遇到问题。我是 SQL 的新手，我第一次使用 2 个表。结果显示在 DataGridView 中，但无法将它们保存到数据库中。我尝试了很多方法，但我无法将 Datagrid 保存到数据库中。

基本上，我会尝试将 DataGridView3 的结果导出到另一个表中，以使它们显示在 Form2 上的报告中。

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

namespace TestDB2
{
    public partial class Form1 : Form
    {

        Form2 fr2 = new Form2();

        SqlConnection cn = new SqlConnection();
        // SqlCommand cmd = new SqlCommand();
        SqlDataReader dr;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            cn.ConnectionString = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;Connect Timeout=30";
            // TODO: This line of code loads data into the 'database1DataSet.Table1' table. You can move, or remove it, as needed.
            this.table1TableAdapter.Fill(this.database1DataSet.Table1);
            // TODO: This line of code loads data into the 'database1DataSet.Table2' table. You can move, or remove it, as needed.
            this.table2TableAdapter.Fill(this.database1DataSet.Table2);
            textBox1.Text = monthCalendar1.TodayDate.ToString();


        }

        private void button1_Click(object sender, EventArgs e)
        {
            //  timer1.Enabled = true;

            database1DataSet.Table2.Clear();


            try
            {


                dataGridView2.Rows.Clear();
                // cmd.CommandText = "Select [First Last Name] from Custumers where Arrival=@arr";
                SqlCommand cmd = new SqlCommand("Select * from Table1 where Date2 >= @arr");
                cmd.Connection = cn;
                cmd.Parameters.AddWithValue("@arr", monthCalendar1.SelectionStart.Date);
                cmd.Parameters.AddWithValue("@arr1", monthCalendar1.SelectionStart.Date.AddDays(1));
                cn.Open();
                dr = cmd.ExecuteReader();

                if (dr.HasRows)
                {

                    while (dr.Read())
                    {

                        dataGridView2.Rows.Add(dr[0].ToString(), dr[1].ToString(), dr[2].ToString(), dr[3].ToString());


                        int i = Convert.ToInt32(dr[0]);
                        string q = Convert.ToString(dr[1]);
                        DateTime w = Convert.ToDateTime(dr[2]);
                        DateTime r = Convert.ToDateTime(dr[3]);
                        this.database1DataSet.Table2.Rows.Add(i, q, w, r);

                        // this.database1DataSet.Table2.AddTable2Row(i, q, w, r).AcceptChanges();
                        // this.database1DataSet.Table2.GetChanges();

                        // cmd.CommandText = "INSERT into Table2 (Id,Name,Date1,Date2) VALUES (@ar,@ar1,@ar2,@ar3)";

                    }



                }
                dr.Close();



                /*
                for (int i = 0; i < dataGridView2.Rows.Count; i++)
                {
                    cmd.CommandText = @"INSERT INTO Table2 (Id) VALUES ('" + dataGridView2.Rows[i].Cells["ID"].Value + "')";
                    cmd.ExecuteNonQuery();
                }
                this.Validate();
                */
                this.Validate();
                cn.Close();
               // textBox1.Text = dataGridView3.Rows[2].Cells[1].Value.ToString();
              //  fr2.ShowDialog();

            }
            catch (Exception ex) { MessageBox.Show(ex.Message.ToString()); cn.Close(); }
        }

        private void monthCalendar1_DateChanged(object sender, DateRangeEventArgs e)
        {
            textBox1.Text = monthCalendar1.SelectionStart.Date.ToString();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {

            try
            {
                string sql = "INSERT INTO Table2 (Id, Name, Date1, Date2) VALUES (@A, @B, @C, @D)";
                using (SqlConnection conn = cn)
                {
                    conn.Open();
                    for (int i = 0; i < dataGridView3.Rows.Count; i++)
                    {

                        SqlCommand cmd = conn.CreateCommand();
                        cmd.CommandText = sql;
                        cmd.Parameters.AddWithValue("@A", dataGridView3.Rows[i].Cells[0].Value.ToString());
                        cmd.Parameters.AddWithValue("@B", dataGridView3.Rows[i].Cells[1].Value.ToString());
                        cmd.Parameters.AddWithValue("@C", dataGridView3.Rows[i].Cells[2].Value.ToString());
                        cmd.Parameters.AddWithValue("@D", dataGridView3.Rows[i].Cells[3].Value.ToString());
                        cmd.ExecuteNonQuery();

                    }
                    conn.Close();
                }


            }
            catch (Exception ex) { MessageBox.Show(ex.Message.ToString()); }

        }
    }
}

Answer 1

努力改变

      cmd.Parameters.AddWithValue("@A", dataGridView3.Rows[i].Cells[0].Value.ToString());

到

     cmd.Parameters.AddWithValue("@A", dataGridView3.Rows[i].Cells[0].Text);