两个DropDownList之间如何建立控制的先后关系?(比如先选省份,后才能选城市) 如果一个页面里有两个DropDownList ,其中先选择一个ddlCategory的值,然后另一个dropdownlist2中的内容会随着前一个的内容的变化而发生相应的变化,就比如第一个DropDownList 控制的是省份,而另一个DropDownList2 控制的是哪个城市,比如选择的是江苏省,那么第二个DropDownList2 中将会跳出的是江苏省的所有城市列表. 那么现在问题是 DropDownList2 绑定了所有的字段了 不按分类来显示了.
请问DropDownList2 怎么得到 ddlCategory 选中的ID号 private void getCategory()//绑定类别下拉列表
{ conn.Open();
string sql = "select * from City";
SqlDataAdapter dr = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
dr.Fill(ds); ddlCategory.DataSource = ds;
ddlCategory.DataTextField = "City";
ddlCategory.DataValueField = "Cid";
ddlCategory.DataBind();
conn.Close();
}
protected void ddlCategory_SelectedIndexChanged(object sender, EventArgs e)
{
conn.Open();
string sql = "select * from Citys where Cid = ???? ";
SqlDataAdapter dr = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
dr.Fill(ds);
DropDownList2.DataSource = ds;
DropDownList2.DataTextField = "City";
DropDownList2.DataValueField = "Cityid";
DropDownList2.DataBind();
conn.Close();
}
请问DropDownList2 怎么得到 ddlCategory 选中的ID号 private void getCategory()//绑定类别下拉列表
{ conn.Open();
string sql = "select * from City";
SqlDataAdapter dr = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
dr.Fill(ds); ddlCategory.DataSource = ds;
ddlCategory.DataTextField = "City";
ddlCategory.DataValueField = "Cid";
ddlCategory.DataBind();
conn.Close();
}
protected void ddlCategory_SelectedIndexChanged(object sender, EventArgs e)
{
conn.Open();
string sql = "select * from Citys where Cid = ???? ";
SqlDataAdapter dr = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
dr.Fill(ds);
DropDownList2.DataSource = ds;
DropDownList2.DataTextField = "City";
DropDownList2.DataValueField = "Cityid";
DropDownList2.DataBind();
conn.Close();
}
void BindCategory(string parentId)
{
conn.Open();
string sql = "select * from Citys where Cid = " + parentId;
SqlDataAdapter dr = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
dr.Fill(ds);
DropDownList2.DataSource = ds;
DropDownList2.DataTextField = "City";
DropDownList2.DataValueField = "Cityid";
DropDownList2.DataBind();
conn.Close(); }
protected void ddlCategory_SelectedIndexChanged(object sender, EventArgs e)
{
BindCategory(ddlCategory.SelectedValue); }