How to populate combo box from database and insert new item on index zero in C#

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This code below works for me, but i have not been able to insert ---Select--- to the for first index with value zero.

What I have tried:

private void LoadGrade()
    {
        using (SQLiteConnection conn = new SQLiteConnection(connstring))
        {

            try
            {
                string query = "select GradeCode, GradeName from Grade";
                SQLiteDataAdapter da = new SQLiteDataAdapter(query, conn);
                conn.Open();
                DataSet ds = new DataSet();
                da.Fill(ds, "OrgGrade");
                cboGrade.Items.Insert(0,"---Select---);
                cboGrade.DisplayMember = "GradeName";
                cboGrade.ValueMember = "GradeCode";
                cboGrade.DataSource = ds.Tables["OrgGrade"];

            }
            catch (Exception ex)
            {

                MessageBox.Show("Error occured loading grade!");
            }
        }
    }

but it is not working for me. Also i want to able to retrieve and display the displaymember and displayvalue on the combo box while retrieving from database without items not being repeated

Posted 14-Sep-17 17:56pm

Uwakpeter

Updated 14-Sep-17 20:41pm

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3 solutions

Solution 1

You can't work directly on the ComboBox as you have bound it to a DataSet. Instead, you need to work with where the data is located using DataRowCollection.InsertAt Method (DataRow, Int32) (System.Data)[^]

So example could be (untested):

C#

var insertRow = ds.Details.NewDetailsRow();

insertRow.Id = "0";
insertRow.Description = "---Select---";

ds.Details.Rows.InsertAt(insertRow, 0);

Posted 14-Sep-17 18:06pm

Graeme_Grant

Comments

Uwakpeter 15-Sep-17 0:10am

Where is the Details from?

Graeme_Grant 15-Sep-17 0:19am

Just off the top of my head, hence "(untested)". Have a look at the link provided.

Solution 4

private void LoadGrade()
    {
        using (SQLiteConnection conn = new SQLiteConnection(connstring))
        {
 
            try
            {
                string query = "select GradeCode, GradeName from Grade";
                SQLiteDataAdapter da = new SQLiteDataAdapter(query, conn);
                conn.Open();
                DataSet ds = new DataSet();
                da.Fill(ds, "OrgGrade");
                
                cboGrade.DisplayMember = "GradeName";
                cboGrade.ValueMember = "GradeCode";
                cboGrade.DataSource = ds.Tables["OrgGrade"];
                cboGrade.Items.Insert(0,"---Select---);
 
            }
            catch (Exception ex)
            {
 
                MessageBox.Show("Error occured loading grade!");
            }
        }
    }

Posted 14-Sep-17 20:41pm

Sheel Ratan

Updated 14-Sep-17 20:42pm

v2

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Karthik_Mahalingam · Accepted Answer · 2017-09-14T18:33:00

Solution 3

try

DataTable dt = new DataTable();
           dt.Columns.Add("GradeName");
           dt.Columns.Add("GradeCode");
           dt.Rows.Add("aaa", "11");
           var row = dt.NewRow();
           row["GradeName"] = "Select";
           row["GradeCode"] = "0";
           dt.Rows.InsertAt(row, 0);
           cboGrade.DisplayMember = "GradeName";
           cboGrade.ValueMember = "GradeCode";
           cboGrade.DataSource = dt;

Posted 14-Sep-17 18:33pm

Karthik_Mahalingam

Comments

Uwakpeter 15-Sep-17 0:43am

I don't want to hardcord list items: dt.Rows.Add("aaa", "11"); i am getting list items from database

Karthik_Mahalingam 15-Sep-17 0:48am

It's just for an example
You shall use your dataset instead

Karthik_Mahalingam 15-Sep-17 0:49am

var row = ds.Tables["OrgGrade"].NewRow();
row["GradeName"] = "Select";
row["GradeCode"] = "0";
ds.Tables["OrgGrade"].Rows.InsertAt(row, 0);
cboGrade.DisplayMember = "GradeName";
cboGrade.ValueMember = "GradeCode";
cboGrade.DataSource = ds.Tables["OrgGrade"];

Uwakpeter 15-Sep-17 1:08am

Yeah, that works thanks, i also want to be able to insert retrieved displaymember and valuemember into the bounded list without duplication that particular list item, say, i am searching for a employee details, and the employee has a grade of senior staff, senior staff is already bounded to list say on index 4, i want to be able to pick it and display, i have tried cboGrade.Items.Insert(0,retrievedValue), this seems to work, but it is duplicating the retrieved item each time the search button is clicked.

Karthik_Mahalingam 15-Sep-17 1:13am

find that particular item and remove it using "RemoveAt(index);" and the insert the new item

Animesh Datta 15-Sep-17 6:04am

my 5!

Karthik_Mahalingam 15-Sep-17 9:15am

Thank you Animesh Datta