Код: Выделить всё
private void LocationComboBox_DropDown(object sender, EventArgs e)
{
if (!string.IsNullOrEmpty(lastNameTextBox.Text))
{
using PersonsContext dbContext = new PersonsContext();
List filteredResults = new List();
var tempResults = dbContext.Persons
.Where(a => EF.Functions.Collate(a.LastName, "NOCASE") == lastNameTextBox.Text)
.GetType()
.GetProperties()
.Where(a => a.Name == locationTypeComboBox.Text)
.Select(a => a.GetValue(a, null)).FirstOrDefault();
if (tempResults != null)
{
filteredResults.Add(tempResults.ToString());
filteredResults.Sort();
filteredResults = filteredResults.Distinct().ToList();
locationComboBox.Items.Clear();
locationComboBox.Items.AddRange([.. filteredResults]);
locationComboBox.Items.Remove(String.Empty);
}
}
else
{
// todo:
}
}

Подробнее здесь: https://stackoverflow.com/questions/790 ... linq-query