Windows Forms: How to populate ComboBox with data from Database in C#

Step 1: Click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Name your project "LinkCombobox" and then click OK

Step 2: Design your form as below

Step 3: Create an EF Model, then add a category table form northwind database to your Entity Framework Model

Step 4: Add code to handle your form as below

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 LinkCombobox
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            try
            {
                //Load category data
                using (NorthwindEntities db = new NorthwindEntities())
                {
                    cboCategory.DataSource = db.Categories.ToList();
                    cboCategory.ValueMember = "CategoryID";
                    cboCategory.DisplayMember = "CategoryName";
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void cboCategory_SelectionChangeCommitted(object sender, EventArgs e)
        {
            Cursor.Current = Cursors.WaitCursor;
            //Update data to textbox
            Category obj = cboCategory.SelectedItem as Category;
            if (obj != null)
            {
                txtCategoryID.Text = obj.CategoryID.ToString();
                txtCategoryName.Text = obj.CategoryName;
                txtDescription.Text = obj.Description;
            }
            Cursor.Current = Cursors.Default;
        }
    }
}

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