Creating Dependent DropDownLists???

Question

nikichu 0 Newbie Poster

15 Years Ago

Creating Dependent DropDownLists...

Forcing the contents of one DropDownList to change based upon the selection of a value from another DropDownList.
How can do so in C#(Asp.net)

i have kept a dropdownlsits for locations --->
Droploc1 ---of locations
and acording to this i have to bind datas to my second dropdwnlsts
Droplab--which contains labs according to a particular locations

Hope u all have understood this,i will give my code here but its not working!!!

Droplab.Items.Clear();
			SqlConnection cone1 = new SqlConnection(@"Server=sqloledb.1;User ID=sa;password=;Data Source=IRID_BDC1;Initial Catalog=hello");
            string searchVal1=Droploc1.SelectedItem.Text;
			Labwelc.Text=searchVal1;
			string selectSQL1 = "SELECT Lab from Loc_det where Lab='"+searchVal1+"'";
			//string searchVal1=Droploc1.SelectedItem.Text;
			//Response.Write(Droploc1.SelectedItem.Text);
			SqlCommand cmdd = new SqlCommand(selectSQL1, cone1);
			SqlDataReader reader1;
			try
			{
				cone1.Open();
				reader1 = cmdd.ExecuteReader();
				while(reader1.Read())
				{
					ListItem newItem = new ListItem();
					newItem.Text = reader1["Lab"].ToString();
					//newItem.Value = reader1["Slno"].ToString();
					Droplab.Items.Add(newItem);
				}
				reader1.Close();
			}
			catch (Exception err)
			{
				Labwelc.Text = "Error reading list of lab. ";
				Labwelc.Text += err.Message;
			}
			finally
			{
				cone1.Close();
			}

asp.net

2 Contributors
6 Replies
130 Views
5 Days Discussion Span
Latest Post 15 Years Ago Latest Post by nikichu

kameswari 2 Junior Poster in Training

15 Years Ago

hi you need to set the autopostback properties of all dropdownlists to "TRUE" and then you need to write the code in the select-indexchanged event.

kameswari 2 Junior Poster in Training

15 Years Ago

hi ichu,
i have created 2 tables in database. Those are

Locations:
lid -(int)
location - varchar

Labs:
labid - (int)
lid - (int)
labname -(varchar)

In the designview i have taken two dropdownlists namely dropdownlist1 and dropdownlist2. In dropdownlist1 i am binding the location names form the TABLE LOCATIONS ->location. Okay??

Here is the code....

codebehind:

using System.Data.SqlClient;



public partial class _Default : System.Web.UI.Page 
{
    SqlConnection con = new SqlConnection(@"Data Source=WINKC185045-MAB\SQLEXPRESS;Initial Catalog=Records;Integrated Security=True");
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {

            SqlDataAdapter da = new SqlDataAdapter("select distinct location,lid from locations", con);
            DataSet ds = new DataSet();
            da.Fill(ds, "locations");
            DropDownList1.Items.Clear();
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {

                DropDownList1.Items.Add(ds.Tables[0].Rows[i][0].ToString());
                DropDownList1.Items[i].Value = ds.Tables[0].Rows[i][1].ToString();
            }
        }

              
    }
   
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        SqlDataAdapter da2 = new SqlDataAdapter("select labname from labs where lid ='" + DropDownList1.SelectedValue + "'", con);
        DataSet ds2 = new DataSet();
        da2.Fill(ds2, "labs");
        DropDownList2.Items.Clear();
        for (int i = 0; i < ds2.Tables[0].Rows.Count; i++)
        {
            DropDownList2.Items.Add(ds2.Tables[0].Rows[i][0].ToString());
        }


    }
}

Source code:

<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
        </asp:DropDownList>
        &nbsp; &nbsp;
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:RecordsConnectionString %>"
            SelectCommand="SELECT * FROM [table1]"></asp:SqlDataSource><asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True">
            </asp:DropDownList></div>
    </form>
</body>

Hope it solves ur problem. Let me know if u still facing problem with this code.

All the best...

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nikichu 0 Newbie Poster · Answer 1 · 2009-08-10T17:17:58+00:00

hi you need to set the autopostback properties of all dropdownlists to "TRUE" and then you need to write the code in the select-indexchanged event.

hi kameshwari,
thank u....but i have set the autopostback properties of all dropdownlists to "TRUE" and writen the code in the select-indexchanged event.
But ten too,,...its no working,if i select the first one....the page refreshes and all the other controls visibility will be false then.

....IChu

nikichu 0 Newbie Poster · Answer 2 · 2009-08-11T16:17:20+00:00

hi ichu,
i have created 2 tables in database. Those are

Locations:
lid -(int)
location - varchar

Labs:
labid - (int)
lid - (int)
labname -(varchar)

In the designview i have taken two dropdownlists namely dropdownlist1 and dropdownlist2. In dropdownlist1 i am binding the location names form the TABLE LOCATIONS ->location. Okay??

Here is the code....

codebehind:

using System.Data.SqlClient;



public partial class _Default : System.Web.UI.Page 
{
    SqlConnection con = new SqlConnection(@"Data Source=WINKC185045-MAB\SQLEXPRESS;Initial Catalog=Records;Integrated Security=True");
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {

            SqlDataAdapter da = new SqlDataAdapter("select distinct location,lid from locations", con);
            DataSet ds = new DataSet();
            da.Fill(ds, "locations");
            DropDownList1.Items.Clear();
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {

                DropDownList1.Items.Add(ds.Tables[0].Rows[i][0].ToString());
                DropDownList1.Items[i].Value = ds.Tables[0].Rows[i][1].ToString();
            }
        }

              
    }
   
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        SqlDataAdapter da2 = new SqlDataAdapter("select labname from labs where lid ='" + DropDownList1.SelectedValue + "'", con);
        DataSet ds2 = new DataSet();
        da2.Fill(ds2, "labs");
        DropDownList2.Items.Clear();
        for (int i = 0; i < ds2.Tables[0].Rows.Count; i++)
        {
            DropDownList2.Items.Add(ds2.Tables[0].Rows[i][0].ToString());
        }


    }
}

Source code:

<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
        </asp:DropDownList>
        &nbsp; &nbsp;
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:RecordsConnectionString %>"
            SelectCommand="SELECT * FROM [table1]"></asp:SqlDataSource><asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True">
            </asp:DropDownList></div>
    </form>
</body>

Hope it solves ur problem. Let me know if u still facing problem with this code.

All the best...

data is not binding into dropdownlist......

its completely left blank.................

kameswari 2 Junior Poster in Training · Answer 3 · 2009-08-11T16:37:18+00:00

hav u created the tables as mentioned above??

code for sql: Locations table

USE [Records]
GO
/****** Object:  Table [dbo].[locations]    Script Date: 08/11/2009 16:04:43 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[locations](
	[location] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
	[lid] [int] NULL
) ON [PRIMARY]

code for LABS table:

USE [Records]
GO
/****** Object:  Table [dbo].[labs]    Script Date: 08/11/2009 16:05:00 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[labs](
	[lid] [int] NULL,
	[labname] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
	[labid] [int] NULL
) ON [PRIMARY]

THE above code is working in my system... try by creating like above...

nikichu 0 Newbie Poster · Answer 4 · 2009-08-12T16:42:06+00:00

hav u created the tables as mentioned above??

code for sql: Locations table

USE [Records]
GO
/****** Object:  Table [dbo].[locations]    Script Date: 08/11/2009 16:04:43 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[locations](
	[location] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
	[lid] [int] NULL
) ON [PRIMARY]

code for LABS table:

USE [Records]
GO
/****** Object:  Table [dbo].[labs]    Script Date: 08/11/2009 16:05:00 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[labs](
	[lid] [int] NULL,
	[labname] [nvarchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
	[labid] [int] NULL
) ON [PRIMARY]

THE above code is working in my system... try by creating like above...

My tables--sql serverdb

Loc_mast(table1)

Slno int (Slno(genertes automatically)(PK)
Loc(PK) navarchar2

Loc_det(table2)

Slno int (Slno(genertes automatically)(PK)
Loc navarchar2 Location names(PK)
Lab navarchar2 Lab names
Tot_sys int Total systems in each labs

........ichu