C# Asp.Net-Insert Update Delete and View With Sql Server Database

In the web.config file, add the connection string to your SQL Server database:

using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;

public class DataAccessLayer
{
    private readonly string connectionString = ConfigurationManager.ConnectionStrings["YourConnectionStringName"].ConnectionString;

    public DataTable GetData()
    {
        DataTable dataTable = new DataTable();
        using (SqlConnection con = new SqlConnection(connectionString))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("SELECT * FROM YourTableName", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(dataTable);
        }
        return dataTable;
    }

    public void InsertData(string column1Value, string column2Value, /* add other parameters as needed */)
    {
        using (SqlConnection con = new SqlConnection(connectionString))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("INSERT INTO YourTableName (Column1, Column2 /* add other columns */) VALUES (@Column1, @Column2 /* add other parameters */)", con);
            cmd.Parameters.AddWithValue("@Column1", column1Value);
            cmd.Parameters.AddWithValue("@Column2", column2Value);
            /* add other parameters */
            cmd.ExecuteNonQuery();
        }
    }

    public void UpdateData(int id, string column1Value, string column2Value, /* add other parameters as needed */)
    {
        using (SqlConnection con = new SqlConnection(connectionString))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("UPDATE YourTableName SET Column1 = @Column1, Column2 = @Column2 /* add other columns */ WHERE Id = @Id", con);
            cmd.Parameters.AddWithValue("@Column1", column1Value);
            cmd.Parameters.AddWithValue("@Column2", column2Value);
            /* add other parameters */
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
    }

    public void DeleteData(int id)
    {
        using (SqlConnection con = new SqlConnection(connectionString))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("DELETE FROM YourTableName WHERE Id = @Id", con);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
    }
}

For example, to view data:

DataAccessLayer dal = new DataAccessLayer();
DataTable dataTable = dal.GetData();
// Bind dataTable to a GridView or other controls to display data