C#搜尋(自動完成,AutoComplete)結合SQL資料

textBox1.Text = "";
textBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;//先設定textBox的搜尋模式
textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;;//設定來源
AutoCompleteStringCollection acc = new AutoCompleteStringCollection();//宣告acc為字串集合器
DataRow[] dr = hw2DataSet.Communication.Select();//宣告DataRow物件陣列，並用Select指令將資料表存入
for (int i = 0; i < dr.Length; i++)
{
    acc.Add(dr[i][comboBox1.SelectedItem.ToString()].ToString().Trim());//將指定欄位內的資料值加入字串集合器
}
textBox1.AutoCompleteCustomSource = acc;//將textBox1的AutoCompleteCustomSource屬性設定為acc