C#

int tbNo = 0;
foreach (control c in MyGroupBox.Controls)
   {
   if (c is TextBox tb)
      {
      tb.Visible = tbNo++ < numberYouWantToSee;
      }
   }

catch (Exception ex)
   {
   Debug.WriteLine(ex.Message);
   }

if (!File.Exists(databaseName))
    {
    using (SQLiteConnection sqliteCon = new SQLiteConnection(@"Data Source = " + databaseName))
        {
        sqliteCon.Open();
        string dbCreationScript = null;
        try
            {
            dbCreationScript = File.ReadAllText(pathToFile);
            using (SQLiteCommand cmd = new SQLiteCommand())
                {
                cmd.CommandText = dbCreationScript;
                cmd.Connection = sqliteCon;
                cmd.ExecuteNonQuery();
                }
            }
        catch (Exception ex)
            {
            Debug.WriteLine(ex.Message);
            }
        }
    }

string dbCreationScript

using System;

public class Program
	{
	static string name = "???";
	static string xxx = $"Hello {name}!";
	static string yyy = "Hello {0}!";
	public static void Main()
	{
		name = "Paul";
		Console.WriteLine($"Hello {name}!");
		Console.WriteLine(xxx);
		Console.WriteLine(yyy, name);
	}
}

Hello Paul!
Hello ???!
Hello Paul!

if (myCheck.Checked)
   {
   myList.Add($"Column2 = '{checked_item2[n]}'");
   }

DataTable filteredTable = dv.ToTable();//dv is DataView

private void TwoDGVs_Shown(object sender, EventArgs e)
    {
    string strConnect = SMDBSupport.SMInstanceStorage.GetInstanceConnectionString(DBName);
    DataTable dt = new DataTable();
    using (SqlConnection con = new SqlConnection(strConnect))
        {
        try
            {
            con.Open();
            using (SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM MyTable", con))
                {
                da.SelectCommand.Parameters.AddWithValue("@SEARCH", "The text to search for");
                da.Fill(dt);
                }
            }
        catch (Exception ex)
            {
            Debug.WriteLine(ex.ToString());
            }
        }
    DataView dv = new DataView(dt);
    Source.DataSource = dv;
    }

private void Filter_TextChanged(object sender, EventArgs e)
    {
    if (Source.DataSource is DataView dv)
        {
        dv.RowFilter = $"Title LIKE '%{Filter.Text}%'";
        DataTable dt = dv.ToTable();
        Destination.DataSource = dt;
        }
    }

Column2 IN ('{checked_item2.Join("', '")}')"