Set Windows Form DataGridView ComboBoxColumn selected value using C# and VB.Net

Hi thewall813,

Refer below example.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

Namespaces

C#

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

VB.Net

Imports System.Data
Imports System.Data.SqlClient

Code

C#

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

    private void Form1_Load(object sender, EventArgs e)
    {
        dataGridView1.DataSource = this.GetData("SELECT TOP 5 CustomerId,ContactName,City,Country FROM Customers");
        dataGridView1.AllowUserToAddRows = false;
    }

    private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        if (e.ColumnIndex == 1 && dataGridView1.Rows[e.RowIndex].Cells[1].Value != null)
        {
            string name = dataGridView1.Rows[e.RowIndex].Cells[1].Value.ToString();
            DataTable dt = this.GetData(string.Format("SELECT CustomerId,ContactName,City,Country FROM Customers WHERE ContactName = '{0}'", name));
            dataGridView2.DataSource = dt;
            dataGridView2.AllowUserToAddRows = false;
            var colCity = this.dataGridView2.Columns[2];
            this.dataGridView2.Columns.Remove(colCity);

            var cmbColumn = new DataGridViewComboBoxColumn();
            cmbColumn.DataSource = this.GetData("SELECT DISTINCT City FROM Customers");
            cmbColumn.DataPropertyName = "City";
            cmbColumn.ValueMember = "City";
            cmbColumn.DisplayMember = "City";
            cmbColumn.HeaderText = "City";
            cmbColumn.ValueType = typeof(string);
            cmbColumn.DefaultCellStyle.NullValue = "";
            this.dataGridView2.Columns.Insert(2, cmbColumn);
        }
    }

    private DataTable GetData(string sql)
    {
        using (SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Northwind;uid=sa;pwd=pass@123;"))
        {
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                cmd.CommandType = CommandType.Text;
                using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
                {
                    using (DataTable dt = new DataTable())
                    {
                        sda.Fill(dt);
                        return dt;
                    }
                }
            }
        }
    }
}

VB.Net

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        dataGridView1.DataSource = Me.GetData("SELECT TOP 5 CustomerId,ContactName,City,Country FROM Customers")
        dataGridView1.AllowUserToAddRows = False
    End Sub

    Private Sub dataGridView1_CellClick(ByVal sender As Object, ByVal e As DataGridViewCellEventArgs) Handles dataGridView1.CellClick
        If e.ColumnIndex = 1 AndAlso dataGridView1.Rows(e.RowIndex).Cells(1).Value IsNot Nothing Then
            Dim name As String = dataGridView1.Rows(e.RowIndex).Cells(1).Value.ToString()
            Dim dt As DataTable = Me.GetData(String.Format("SELECT CustomerId,ContactName,City,Country FROM Customers WHERE ContactName = '{0}'", name))
            dataGridView2.DataSource = dt
            dataGridView2.AllowUserToAddRows = False
            Dim colCity = Me.dataGridView2.Columns(2)
            Me.dataGridView2.Columns.Remove(colCity)
            Dim cmbColumn = New DataGridViewComboBoxColumn()
            cmbColumn.DataSource = Me.GetData("SELECT DISTINCT City FROM Customers")
            cmbColumn.DataPropertyName = "City"
            cmbColumn.ValueMember = "City"
            cmbColumn.DisplayMember = "City"
            cmbColumn.HeaderText = "City"
            cmbColumn.ValueType = GetType(String)
            cmbColumn.DefaultCellStyle.NullValue = ""
            Me.dataGridView2.Columns.Insert(2, cmbColumn)
        End If
    End Sub

    Private Function GetData(ByVal sql As String) As DataTable
        Using con As SqlConnection = New SqlConnection("Data Source=.;Initial Catalog=Northwind;uid=sa;pwd=pass@123;")
            Using cmd As SqlCommand = New SqlCommand(sql, con)
                cmd.CommandType = CommandType.Text
                Using sda As SqlDataAdapter = New SqlDataAdapter(cmd)
                    Using dt As DataTable = New DataTable()
                        sda.Fill(dt)

                        Return dt
                    End Using
                End Using
            End Using
        End Using
    End Function
End Class

Screenshot