c# combobox selectedindexchanged events

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Can anyone help me with how to populate a combobox with data once another combobox has been selected? I'm confused as to how the selectedindexchanged events work. I am using C# with Visual Studio 2010/2012.

Posted 10-Sep-12 18:33pm

joshrduncan2012

Updated 24-Jun-21 19:57pm

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Member 15261963 25-Jun-21 3:58am

Combobox change system date and time ?
Plz give me answer...

4 solutions

Solution 4

suppose we have 2 tables one containing records of student and other containing their subjects

we have 2 combo box one for students and other for their subjects

'''' giving value to first combobox

C#

dataset ds = new dataset() ;
string querry = "select studentid,studentname from tbstudent";
sqlcommand cmd = new sqlcommand(querry,connection);
dataadapter da = new sqldataadapter(cmd);
combobox1.valuemember = "studentid";
combobox1.displaymember = "studentname";
combobox1.datasource = ds.tables(0);

now on combobox1 selected index event

C#

dataset ds = new dataset() ;
 string querry = "select subjectid,subjectname from tbsubject where studentid = combobox1.selectedvalue";
 sqlcommand cmd = new sqlcommand(querry,connection);
 dataadapter da = new sqldataadapter(cmd);
 combobox2.valuemember = "subjectid";
 combobox2.displaymember = "subjectname ";
 combobox2.datasource = ds.tables(0);

Posted 10-Sep-12 19:29pm

vijay bisht

Updated 10-Sep-12 22:41pm

v3

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Mohamed Mitwalli · Accepted Answer · 2012-09-10T19:19:00

Hi ,
Check this

C#

private void Form1_Load(object sender, EventArgs e)
        {
         DataTable dt  = new DataTable();
        using (SqlConnection Cn = new SqlConnection(Properties.Settings.Default.con))
        {
            using (SqlCommand Cmd = new SqlCommand("SELECT * FROM  Orders  where oid = @oid", Cn))
            {
                Cn.Open();            
               SqlDataAdapter  adpt = new SqlDataAdapter(Cmd);
                adpt.Fill(dt);
                comboBox1.DataSource = dt;
                comboBox1.DisplayMember="Orders";
                comboBox1.ValueMember="id";
            }
        }
     }
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
        DataTable dt  = new DataTable();
        using (SqlConnection Cn = new SqlConnection(Properties.Settings.Default.con))
        {
            using (SqlCommand Cmd = new SqlCommand("SELECT * FROM  OrdersDetails  where oid = @oid", Cn))
            {
                Cn.Open();
                Cmd.Parameters.AddWithValue("@oid" ,Convert.ToInt32( comboBox1.SelectedValue));
               SqlDataAdapter  adpt = new SqlDataAdapter(Cmd);
                adpt.Fill(dt);
                comboBox2.DataSource = dt;
                comboBox2.DisplayMember="amount";
                comboBox2.ValueMember="id";
            }

        }
      
    }

Best Regards
M.Mitwalli

Prasad_Kulkarni · Accepted Answer · 2012-09-10T18:40:00

Solution 2

If you are talking about cascading dropdownlist then have a look:

Selecting value in cascading dropdown list dynamically[^]
How to populate a dropdown list with another ddl[^]
Cascading DropDown - Country to state[^]

ASP.NET cascading drop-down-list (CSASPNETCascadingDropDownList)[^]
CascadingDropDown Demonstration[^]
Cascading DropDownList in ASP.NET MVC[^]
Creating Cascading DropDownLists in ASP.Net[^]
Using CascadingDropDown with a Database[^]

Posted 10-Sep-12 18:40pm

Prasad_Kulkarni

Comments

ridoy 11-Sep-12 1:20am

owao!plenty of links..+5

Prasad_Kulkarni 11-Sep-12 2:01am

Thank you Ridoy!

Mohamed Mitwalli 11-Sep-12 1:25am

5+ For web :)

Prasad_Kulkarni 11-Sep-12 2:02am

Thank you Mohamed!

__TR__ 11-Sep-12 8:32am

+5

Prasad_Kulkarni 11-Sep-12 8:33am

Thank you Tejas!

**JF2015** · Accepted Answer · 2012-09-10T18:39:00

Here is some sample code:

C#

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
   comboBox2.Items.Clear();
   if (comboBox1.SelectedItem.ToString() == "1")
   {
      comboBox2.Items.Add("Hello");
      comboBox2.Items.Add("World");
   }
   else
   {
      comboBox2.Items.Add("Test1");
      comboBox2.Items.Add("Test2");
   }
}

just subscribe to the first combobox SelectedIndexChanged event and in the event handler change the content of the second combo box.