Combox绑定数据/带查询功能

private void button3_Click(object sender, EventArgs e)
{
string sql = "select dname,did from department";

SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;User ID=sa;Password=123456");
try
{
SqlCommand cmd = new SqlCommand(sql, conn);
conn.Open();
SqlDataReader reader= cmd.ExecuteReader();

//将数据绑定到列表框中
cboList.Items.Clear();
//通过循环读取每一行的数据
while (reader.Read())//延迟执行
{
//使用索引器读取数据
//reader[1]
//reader["dname"]
//使用方法的方式读取，不需要进行类型转换
string dname=reader.GetString(0);//参数为列的索引
//注意：这里的索引，不是根据表的结构来确定的，而是根据select子句的结果集决定的
cboList.Items.Add(dname);

cboList.AutoCompleteMode = AutoCompleteMode.SuggestAppend;//查询功能
cboList.AutoCompleteSource = AutoCompleteSource.ListItems;//查询功能
}
reader.Close();
reader.Dispose();
cmd.Dispose();

//cmd.CommandText = "";
}
catch
{
//...
}
finally
{
conn.Close();
conn.Dispose();
}
}

private void cbTitle_SelectedIndexChanged(object sender, EventArgs e)
{
textBox1.Text = cbTitle.SelectedItem.ToString();//下拉框值传入其它组件中

}

private void button4_Click(object sender, EventArgs e)
{
string sql = "select dname,did from department";
using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;user id=sa;Password=123456"))
{
SqlCommand cmd = new SqlCommand(sql, conn);
conn.Open();//尽量晚的打开连接，尽量早的关闭连接
SqlDataReader reader = cmd.ExecuteReader();

//将数据绑定到列表
cboList.Items.Clear();
while (reader.Read())
{
Department d1 = new Department() {Did=reader.GetInt32(1),Dname=reader.GetString(0)};
cboList.Items.Add(d1);
cboList.DisplayMember = "Dname";//指定对象的某个属性用于显示
}
reader.Close();
reader.Dispose();
}
}

private void button5_Click(object sender, EventArgs e)
{
//1、构造sql语句
string sql = "select * from department";
//2建立连接
using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=hem09;User id=sa;Password=123456"))
{
//3.1构造命令对象
SqlCommand cmd = new SqlCommand(sql, conn);
//2.1打开连接
conn.Open();
//3.2执行命令
using (SqlDataReader reader = cmd.ExecuteReader())
{
//清空原有数据
gvList.Rows.Clear();
gvList.Columns.Clear();
//新建列
gvList.Columns.Add("did","编号");
gvList.Columns.Add("dname", "名称");
//遍历查询结果集，将数据添加到列表中
while (reader.Read())
{
Department d1 = new Department() { Did = reader.GetInt32(0), Dname = reader.GetString(1) };
gvList.Rows.Add(d1.Did, d1.Dname);
}
}
cmd.Dispose();
}
}