效果如下：

【方法一】 使用TextBox

步骤如下：

1. 在界面拖放一个TextBox控件(Name属性为TextBox1)，
2. 在窗体加载函数中加入如下代码：

try

{

string value = this.TextBox1.Text.Trim();

string sql = "select 姓名 from studentsScore";

DataSet ds = SqlManage.DataSelect(sql);

this.TextBox1.AutoCompleteCustomSource.Clear();

foreach (DataRow row in ds.Tables[0].Rows)

{

this.TextBox1.AutoCompleteCustomSource.Add(row["姓名"].ToString());

}

this.TextBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;

this.TextBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;

}

catch (Exception ex)

{

MessageBox.Show(ex.Message.ToString());

}

【方法二】  使用ComboBox

AutoCompleteStringCollection str = new AutoCompleteStringCollection();

cbox.AutoCompleteMode = AutoCompleteMode.SuggestAppend;

cbox.AutoCompleteSource = AutoCompleteSource.CustomSource;

cbox.AutoCompleteCustomSource = str;

foreach (DataRow dr in tdt.Rows)

{

    cbox.AutoCompleteCustomSource.Add(dr[0].ToString());

    cbox.Items.Add(dr[0].ToString());

}

tdt为DataTable类型， cbox为ComboBox控件.