Linq to sql server thêm, sửa, xóa danh mục

 Hướng dẫn linq to sql server thêm, xóa, sửa danh mục có điều kiện.

Code hướng dẫn thêm xóa sửa bằng linq to sql

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 LinqToSQL

{

    public partial class frmDanhMuc : Form

    {

        public frmDanhMuc()

        {

            InitializeComponent();

        }

        private void frmDanhMuc_Load(object sender, EventArgs e)

        {

            hiendanhmuclenlistbox();

        }

 

        private void hiendanhmuclenlistbox()

        {

CSDLLINQDATADataContext contex = new CSDLLINQDATADataContext();

            List<DanhMuc> csdldm = contex.DanhMucs.ToList();

            lstDanhMuc.DataSource = csdldm;

            lstDanhMuc.ValueMember = "MaDM";

            lstDanhMuc.DisplayMember = "TenDM";

            dautien = true;

        }

        private void tbtLuu_Click(object sender, EventArgs e)

        {

            try

            {

 CSDLLINQDATADataContext contex = new CSDLLINQDATADataContext();

                DanhMuc dm = new DanhMuc();

                dm.MaDM = int.Parse(txtMaDM.Text);

                dm.TenDM = txtTenDM.Text;

                contex.DanhMucs.InsertOnSubmit(dm);

                contex.SubmitChanges(); // xách nhận lưu

                hiendanhmuclenlistbox();

                txtMaDM.Clear();

                txtTenDM.Clear();

                txtMaDM.Focus();

                MessageBox.Show(" Bạn đã thêm thành công");

            }

            catch (Exception ex)

            {

 

                MessageBox.Show(ex.Message);

            }

        }

        private void button2_Click(object sender, EventArgs e)

        {

            try

            {

CSDLLINQDATADataContext contex = new CSDLLINQDATADataContext();

                int madm = int.Parse(txtMaDM.Text);

                DanhMuc dm = contex.DanhMucs.FirstOrDefault(x => x.MaDM == madm);

                dm.TenDM = txtTenDM.Text;

                contex.SubmitChanges();

                MessageBox.Show(" sửa thành công");

                hiendanhmuclenlistbox();

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

        }

        bool dautien = false;

private void lstDanhMuc_SelectedIndexChanged(object sender, EventArgs e)

        {

           if (dautien==false)

            {

                return;

            }

            if (lstDanhMuc.SelectedValue == null)

            {

                return;

            }

            DanhMuc dm = lstDanhMuc.SelectedItem as DanhMuc;

           

                txtMaDM.Text = dm.MaDM + "";

                txtTenDM.Text = dm.TenDM; 

    

        }

        private void button3_Click(object sender, EventArgs e)

        {

            if (lstDanhMuc.SelectedValue==null)

            {

                return;

            }

            try

            {

                CSDLLINQDATADataContext contex = new CSDLLINQDATADataContext();

                int ma = int.Parse(txtMaDM.Text);

                DanhMuc dm = contex.DanhMucs.FirstOrDefault(x => x.MaDM == ma);

                if (dm!=null)

                {

                    if (dm.SanPhams.Count>0)

                    {

MessageBox.Show("Không thẻ xóa[" + dm.TenDM + "] vì có sản phẩm [" + dm.SanPhams.Count + "]");

                        return;

                    }

                    contex.DanhMucs.DeleteOnSubmit(dm);

                    contex.SubmitChanges();

                    MessageBox.Show(" Xóa thành công");

                }

               

                hiendanhmuclenlistbox();

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

        }

    }

}