Пример кода C# работа с базой данных

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using FirebirdSql.Data.FirebirdClient;

namespace HOTEL
{
    public partial class Client : Form
    {
        public Client()
        {
            InitializeComponent();
           
        }

        private void pERSONBindingNavigatorSaveItem_Click(object sender, EventArgs e)
        {
            this.Validate();
            this.pERSONBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.dataSet1);

        }

        private void Client_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'dataSet1.PERSON' table. You can move, or remove it, as needed.
            this.pERSONTableAdapter.Fill(this.dataSet1.PERSON);
            // TODO: This line of code loads data into the 'dataSet1.PERSON' table. You can move, or remove it, as needed.
            this.pERSONTableAdapter.Fill(this.dataSet1.PERSON);
            // TODO: This line of code loads data into the 'dataSet1.PERSON' table. You can move, or remove it, as needed.
           // this.pERSONTableAdapter.Fill(this.dataSet1.PERSON);
            

        }

        private void pERSONBindingNavigatorSaveItem_Click_1(object sender, EventArgs e)
        {
            this.Validate();
            this.pERSONBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.dataSet1);

        }

        private void button1_Click(object sender, EventArgs e)
        {
            NewClient nc = new NewClient();
            nc.Show();
        }

        private void pERSONBindingNavigatorSaveItem_Click_2(object sender, EventArgs e)
        {
            this.Validate();
            this.pERSONBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.dataSet1);

        }

        private void pERSONDataGridView_CellContentDoubleClick(object sender, DataGridViewCellEventArgs e)
        {
            try
            {
                NewReserv nr = (NewReserv)this.Owner;
                if (pERSONDataGridView.CurrentCell != null && pERSONDataGridView.CurrentCell.Value != null)
                {
                    nr.textBox1.Text = pERSONDataGridView.Rows[e.RowIndex].Cells[1].Value.ToString();
                    nr.id_client = Convert.ToInt32(pERSONDataGridView.Rows[e.RowIndex].Cells[0].Value.ToString());
                    Close();
                }
            }
            catch(System.InvalidCastException)
            {
            }
            try
            {
                Occupation nr = (Occupation)this.Owner;
                if (pERSONDataGridView.CurrentCell != null && pERSONDataGridView.CurrentCell.Value != null)
                {
                    nr.textBox1.Text = pERSONDataGridView.Rows[e.RowIndex].Cells[1].Value.ToString();
                    nr.id_client = Convert.ToInt32(pERSONDataGridView.Rows[e.RowIndex].Cells[0].Value.ToString());
                    Close();
                }
            }
            catch (System.InvalidCastException)
            {
            }
            try
            {
                Client_Service cs = (Client_Service)this.Owner;
                if (pERSONDataGridView.CurrentCell != null && pERSONDataGridView.CurrentCell.Value != null)
                {
                    cs.textBox1.Text = pERSONDataGridView.Rows[e.RowIndex].Cells[0].Value.ToString();
                    Close();
                }
            }
            catch (System.InvalidCastException)
            {
            }
            try
            {
                ReportClient cs = (ReportClient)this.Owner;
                if (pERSONDataGridView.CurrentCell != null && pERSONDataGridView.CurrentCell.Value != null)
                {
                    cs.textBox1.Text = pERSONDataGridView.Rows[e.RowIndex].Cells[0].Value.ToString();
                    Close();
                }
            }
            catch (System.InvalidCastException)
            {
            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            if (pERSONDataGridView.DataSource == pERSONBindingSource)
            {
                pERSONBindingSource.Filter = "[surname]LIKE'" + textBox1.Text + "%'";
            }
        }

        private void удалитьToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (pERSONDataGridView.RowCount <= 0)
                return;
            DataRow del = ((DataRowView)pERSONBindingSource.Current).Row;
            string message = "Вы действительно хотите удалить клиента?";
            string caption = "Удаление";
            MessageBoxButtons buttons = MessageBoxButtons.OKCancel;

            MessageBoxIcon icon = MessageBoxIcon.Question;
            // Show message box
            DialogResult result = MessageBox.Show(message, caption, buttons, icon);

            if (result == DialogResult.OK)
            {

                FbCommandBuilder fbCommandBuilder = new FbCommandBuilder(pERSONTableAdapter.Adapter);
                del.Delete();
                pERSONBindingSource.EndEdit();
                pERSONTableAdapter.Adapter.Update(dataSet1, "PERSON");
            }
        }

        private void добавитьИностранцаToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Foreigner f = new Foreigner();
            f.ShowDialog();
        }

        private void добавитьToolStripMenuItem_Click(object sender, EventArgs e)
        {

        }

     
    }
}