VS连接SQL?server数据库及实现基本CRUD操作

using System.Data;
using System.Data.SqlClient;
namespace connect_sql
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
			Table();
        }
		//数据写入，公共的，所有有表格的地方都用的上
		public void Table()
		{
			SqlConnection sqlcon = new SqlConnection();
			sqlcon.ConnectionString = "Data Source=LAPTOP-HIAIVLQI;Initial Catalog=class;Integrated Security=True";
			sqlcon.Open();
			dataGridView1.Rows.Clear();
			string sql = "select * from sc";
			SqlCommand com = new SqlCommand(sql, sqlcon);                
			SqlDataAdapter ada = new SqlDataAdapter(sql, sqlcon);//建立SQL语句与数据库的连接
			DataSet ds = new DataSet();  //实例化Datatable类
			ada.Fill(ds); //添加SQL并且执行                                      
			dataGridView1.DataSource = ds.Tables[0].DefaultView;//显示数据   
		}
 
	}
}

		public void Table()
		{
			SqlConnection sqlcon = new SqlConnection();
			sqlcon.ConnectionString = "Data Source=LAPTOP-HIAIVLQI;Initial Catalog=song;Integrated Security=True";//连接服务器
			sqlcon.Open();
			dataGridView1.Rows.Clear();
			string sql = "select * from people";//SQL语句，可自己编写需要的。
			SqlCommand com = new SqlCommand(sql, sqlcon);                
			SqlDataAdapter ada = new SqlDataAdapter(sql, sqlcon);//建立SQL语句与数据库的连接
			DataSet ds = new DataSet();  //实例化Datatable类
			ada.Fill(ds); //添加SQL并且执行                                      
			dataGridView1.DataSource = ds.Tables[0].DefaultView;//显示数据   
		}