Data is not updated in database. No error!! Searching occurs smoothly, but No insert/update/delete

Question

I am trying to create an employee database. The code gives no error. I can access the database quite smoothly. But, database can't be updated. I am posting my database Connection class portion and insert.cs. guys, please tell me where I made a mistake. So that I can also correct update.cs and delete.cs

This is the database connection class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace employeDB1
{
    class DatabaseConnection
    {
        private string sql_string;
        private string strCon;
        System.Data.SqlClient.SqlDataAdapter da_1;

        public string Sql
        {
            set
            {
                sql_string = value;
            }
        }

        public string connection_string
        {
            set
            {
                strCon = value;
            }
        }

        public System.Data.DataSet GetConnection
        {
            get
            {
                return MyDataSet();
            }
        }

        private System.Data.DataSet MyDataSet()
        {
            System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(strCon);
            con.Open();
            da_1 = new System.Data.SqlClient.SqlDataAdapter(sql_string, con);
            System.Data.DataSet ds = new System.Data.DataSet();
            da_1.Fill(ds);
            con.Close();
            return ds;
        }

        public void UpdateDatabase(System.Data.DataSet ds)
        {
            System.Data.SqlClient.SqlCommandBuilder cb = new System.Data.SqlClient.SqlCommandBuilder(da_1);
            cb.DataAdapter.Update(ds.Tables[0]);
        }
    }
}

Insert.cs

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;

namespace employeDB1
{
    public partial class Insert : Form
    {
        public Insert()
        {
            InitializeComponent();
        }
        DatabaseConnection objConnect;

        string conString;
        int inc = 0;
        int MaxRows;
        DataSet ds = new DataSet();
        DataRow dRow;

        public void Insert_Load(object sender, EventArgs e)
        {
            try
            {
                objConnect = new DatabaseConnection();
                conString = Properties.Settings.Default.EmployeeConnectionString;

                objConnect.connection_string = conString;
                objConnect.Sql = Properties.Settings.Default.SQL;
                ds = objConnect.GetConnection;
                MaxRows = ds.Tables[0].Rows.Count;
            }
            catch(Exception err)
            {
                MessageBox.Show(err.Message);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            DataRow row = ds.Tables[0].NewRow();
            row[0] = int.Parse(textBox1.Text);
            row[1] = textBox2.Text;
            row[2] = textBox3.Text;
            row[3] = int.Parse(textBox4.Text);
            ds.Tables[0].Rows.Add(row);
            try
            {
                objConnect.UpdateDatabase(ds);
                MaxRows = MaxRows + 1;
                inc = MaxRows - 1;
                MessageBox.Show("RECORD INSERTED");
            }
            catch(Exception err)
            {
                MessageBox.Show(err.Message);
            }
        }

        private void NavigateRecords()
        {
            dRow = ds.Tables[0].Rows[inc];
            textBox1.Text = dRow.ItemArray.GetValue(0).ToString();
            textBox2.Text = dRow.ItemArray.GetValue(1).ToString();
            textBox3.Text = dRow.ItemArray.GetValue(2).ToString();
            textBox4.Text = dRow.ItemArray.GetValue(3).ToString();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if(inc > 0)
            {
                inc--;
                NavigateRecords();
            }
            else
            {
                MessageBox.Show("First Record");
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if(inc < MaxRows - 1)
            {
                inc++;
                NavigateRecords();
            }
            else
            {
                MessageBox.Show("Last Record");
            }
        }
    }
}