พอดีพึ่งเรียนรู้เรื่องการเขียน Code C# แล้วมีเพื่อนทักว่าเขียนโค้ดไม่ถูกเลยอยากรุ้ว่า #ผิดตรงไหน #เพราะอะไร #แบบนี้ใช้ได้ไหม รบกวนผู้รู้เรื่องนี้บอกหน่อยค่ะ
ตัอย่างโค้ด ใช้ visual Studio + SQL Server
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace BBGunSystem
{
    public partial class Product : Form
    {
        public Product()
        {
            InitializeComponent();
        }
        DataSet ds = new DataSet();
        String Con = "Data Source=DESKTOP-9MNACAA;Initial Catalog=Roiet System;Integrated Security=True";


        private void Product_Load(object sender, EventArgs e)
        {
         String sql = "SELECT * FROM Product";
            SqlDataAdapter sda = new SqlDataAdapter(sql,Con);
            sda.Fill(ds,"Product");

            GridPro.DataSource = ds.Tables["Product"];

        
        }
         private void GridPro_CellContentClick(object sender, DataGridViewCellEventArgs e)
                {
                    if (e.RowIndex == -1)
                        return;
                    else
                    {
                        GridPro.Rows[e.RowIndex].Selected = true;
                        DataRow dr = ds.Tables["Product"].Rows[e.RowIndex];

                        textBox1.Text = dr["Pid"].ToString();
                        textBox2.Text = dr["Pname"].ToString();
                        textBox3.Text = dr["Vertion"].ToString();
                        textBox4.Text = dr["Color"].ToString();
                        textBox5.Text = dr["Deteil"].ToString();
                        textBox6.Text = dr["Price"].ToString();
                        textBox7.Text = dr["Inventory"].ToString();
                    }
         }
        
        private void S_Click(object sender, EventArgs e)
        {
         DataRow[] drs = ds.Tables["Product"].Select("Pid='"+textBox1.Text+"'");
            if (drs.Length == 0)
                MessageBox.Show("ไม่พบข้อมูล");
            else
            {
                
                textBox2.Text = drs[0]["Pname"].ToString();
                textBox3.Text = drs[0]["Vertion"].ToString();
                textBox4.Text = drs[0]["Color"].ToString();
                textBox5.Text = drs[0]["Deteil"].ToString();
                textBox6.Text = drs[0]["Price"].ToString();
                textBox7.Text = drs[0]["Inventory"].ToString();

            }
        }

        private void Insert_Click(object sender, EventArgs e)
        {
            DataRow[] drs = ds.Tables["Product"].Select("Pid='"+textBox1.Text+"'");
            if (drs.Length == 1)
            

                MessageBox.Show("ข้อมูลซ้ำกัน");
            

            else
            {
                DataRow dr = ds.Tables["Product"].NewRow();
                dr["Pid"] = textBox1.Text;
                dr["Pname"] = textBox2.Text;
                dr["Vertion"] = textBox3.Text;
                dr["Color"] = textBox4.Text;
                dr["Deteil"] = textBox5.Text;
                dr["Price"] = textBox6.Text;
                dr["Inventory"] = textBox7.Text;

                ds.Tables["Product"].Rows.Add(dr);


            }
            GridPro.DataSource = ds.Tables["Product"];

            String sql = "SELECT * FROM Product";
            SqlDataAdapter sda = new SqlDataAdapter(sql, Con);
            SqlCommandBuilder cb = new SqlCommandBuilder(sda);
            sda.Update(ds,"Product");

        }

        private void Delet_Click(object sender, EventArgs e)
        {
            DataRow[] drs = ds.Tables["Product"].Select("Pid='" + textBox1.Text + "'");
            if (drs.Length == 0)
                MessageBox.Show("ไม่พบข้อมูล");
            else
            {
                drs[0].Delete();
                ds.Tables["Product"].AcceptChanges();
            }
            GridPro.DataSource = ds.Tables["Product"];
            String sql = "SELECT * FROM Product";
            SqlDataAdapter sda = new SqlDataAdapter(sql, Con);
            SqlCommandBuilder cb = new SqlCommandBuilder(sda);
            sda.Update(ds, "Product");
        }

        private void Up_Click(object sender, EventArgs e)
        {
            
            DataRow[] drs = ds.Tables["Product"].Select("Pid='" + textBox1.Text + "'");
            if (drs.Length == 0)
                 MessageBox.Show("ไม่พบข้อมูล");
            else
            {
             drs[0]["Pname"] = textBox2.Text;
             drs[0]["Vertion"] = textBox3.Text;
             drs[0]["Color"] = textBox4.Text;
             drs[0]["Deteil"] = textBox5.Text;
             drs[0]["Price"] = textBox6.Text;
             drs[0]["Inventory"] = textBox7.Text;

            }

            GridPro.DataSource = ds.Tables["Product"];
            String sql = "SELECT * FROM Product";
            SqlDataAdapter sda = new SqlDataAdapter(sql, Con);
            SqlCommandBuilder cb = new SqlCommandBuilder(sda);
            sda.Update(ds, "Product");
        }
        private void ออกจากระบบToolStripMenuItem_Click(object sender, EventArgs e)
        {

            if (MessageBox.Show("คุณต้องการจะปิดโปรแกรมหรือไม่ ?", "ปิดโปรแกรม", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2) == DialogResult.Yes)
            {
                Application.Exit();

            }
            else
            {
            
            }
        }

    

        private void toolStripButton2_Click(object sender, EventArgs e)
        {
            this.Hide();
            Member fr = new Member();
            fr.Show();
        }

        
        }
    }