Question

在dropdownlist中添加一个默认项“--请选择--”

我已经在dropdownlist中从数据库中添加了一些项：
SqlCommand cmd = new SqlCommand("select distinct bm from xsbd_yhdl",conn);
SqlDataReader dr = cmd.ExecuteReader();
this.ddl_bm.DataSource = dr;
this.ddl_bm.DataTextField = "bm";
this.ddl_bm.DataBind();
conn.Close();
我想再向ddl_bm中添加一项“--请选择--”让它成为默认的项，代码怎么写？

Answer 1

你应该这样写：
SqlCommand cmd = new SqlCommand("select distinct bm from xsbd_yhdl",conn);
SqlDataReader dr = cmd.ExecuteReader();
this.ddl_bm.DataSource = dr;
this.ddl_bm.DataTextField = "bm";
this.ddl_bm.DataValueField="对应的值";
this.ddl_bm.DataBind();
conn.Close();
ListItem li= new ListItem("--请选择--", "");
this.ddl_bm.Items.Insert(0,li);