Windows Forms: How to Load selected columns data in DataGridView 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 "LoadSelectedCloumns" and then click OK

Step 2: Design your form as below

Form1

Form2

Step 3: Add a connection string to the app.config file as below

<configuration>
  <connectionStrings>
    <add name="cn" connectionString="data source=.;initial catalog=NORTHWND;user id=sa;password=123@qaz;" providerName="System.Data.SqlClient"/>
  </connectionStrings>
</configuration>

Step 4: Add code to handle your form as below

Form1

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

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

        private void btnGetData_Click(object sender, EventArgs e)
        {
            string query = string.Empty;
            foreach (string s in checkedListBox.CheckedItems)
                query += s + ",";
            //Get columns
            query = query.Remove(query.Length - 1, 1);
            string sql = string.Format("select {0} from categories", query);
            using(SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["cn"].ConnectionString))
            {
                if (cn.State == ConnectionState.Closed)
                    cn.Open();
                //Execute query to retrieve data from sql database
                SqlCommand cmd = new SqlCommand(sql, cn) { CommandType = CommandType.Text };
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                using(DataTable dt = new DataTable("Categories"))
                {
                    //Fill data to datatable
                    sda.Fill(dt);
                    using(Form2 frm = new Form2(dt))
                    {
                        frm.ShowDialog();
                    }
                }
            }
        }
    }
}

Form2

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 LoadSelectedCloumns
{
    public partial class Form2 : Form
    {
        public Form2(DataTable dt)
        {
            InitializeComponent();
            dataGridView.DataSource = dt;
        }
    }
}

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