how to fill data in comboBox. but error was found?

Question

try { string connString = @Data Source=VINODKUMAR;Initial Catalog=ShreeSankalp;Persist Security Info=True;User ID=sa;Password=1234567890; using (SqlConnection sqlConn = new SqlConnection(connString)) { string sqlQuery = @SELECT Batch No * from New Batchs; SqlCommand cmd = new SqlCommand(sqlQuery sqlConn); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); //dt.Columns.Add(Batch No typeof (string)); comboBox1.DisplayMember = Batch No; comboBox1.DataSource = dt; } } catch (Exception ex) { MessageBox.Show(ex.ToString()); MessageBox.Show(Please Enter Admission ID); }

Raja T · Answer

try { con.Open(); da = new SqlDataAdapter(select BatchNo from Batches  con); dt = new DataTable(); da.Fill(dt); //DataRow dr; //dr = dt.NewRow(); //dr.ItemArray = new object[] { 0 ---Select an item--- }; //dt.Rows.InsertAt(dr 0); comboBox1.DisplayMember = BatchNo; comboBox1.ValueMember = S.No; comboBox1.DataSource = dt; con.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } Which code are tried above code?

vinod jangir · Answer

yes i try but same problem

Raja T · Answer

Are you tried my solution?

vinod jangir · Answer

try { con.Open(); da = new SqlDataAdapter(select BatchNo from Batches  con); dt = new DataTable(); da.Fill(dt); //DataRow dr; //dr = dt.NewRow(); //dr.ItemArray = new object[] { 0 ---Select an item--- }; //dt.Rows.InsertAt(dr 0); comboBox1.DisplayMember = BatchNo; comboBox1.ValueMember = S.No; comboBox1.DataSource = dt; con.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } I Got this problem Object reference not set to an instance of an object.

Raja T · Answer

Hi Vinod try like string sqlQuery = @SELECT BatchNo from Batches; SqlCommand cmd = new SqlCommand(sqlQuery sqlConn); SqlDataAdapter da = new SqlDataAdapter(cmd); DataSet ds = new DataSet(); da.Fill(ds); comboBox1.ValueMember = BatchNo; comboBox1.DisplayMember = BatchNo; comboBox1.DataSource = ds.Tables[0]; Note : Please check in debug mode data set contains data or not

vinod jangir · Answer

comboBox2.DisplayMember =  BatchNo ; but same problem

Manas Mohapatra · Answer

string sqlQuery = @SELECT BatchNo from Batches; SqlCommand cmd = new SqlCommand(sqlQuery sqlConn); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); comboBox2.DataSource = dt; comboBox2.ValueMember = BatchNo; comboBox2.DisplayMember =  S.No ; See above two yellow marked code. You are fetching only BatchNo column in your query and you are using S.No as DisplayMember in combobox. Either you need fetch that column from DB or you need to use BatchNo as DisplayMember. comboBox2.DisplayMember =  BatchNo ;

vinod jangir · Answer

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Data.SqlClient; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace ShriSankalp { public partial class Attendance : Form { public Attendance() { try { string connString = @Data Source=VINODKUMAR;Initial Catalog=ShreeSankalp;Persist Security Info=True;User ID=sa;Password=1234567890; using (SqlConnection sqlConn = new SqlConnection(connString)) { string sqlQuery = @SELECT BatchNo from Batches; SqlCommand cmd = new SqlCommand(sqlQuery sqlConn); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); comboBox1.DataSource = dt; comboBox1.ValueMember = BatchNo; comboBox1.DisplayMember = S.No; } } catch (Exception ex) { MessageBox.Show(ex.ToString()); MessageBox.Show(Please Enter Admission ID); } InitializeComponent(); } private void button1_Click(object sender EventArgs e) { StuAtedLit reg = new StuAtedLit(); reg.Show(); } private void button2_Click(object sender EventArgs e) { this.Close(); } } } it check comboBox1.DataSource = dt; and got error Object reference not set to an instance of an object.

Manas Mohapatra · Answer

Please provide in which line you are getting exact error and also provide whole code.

vinod jangir · Answer

same problem.

Abhishek Singh · Answer

Please try to bind first .. comboBox1.DataSource = dt; comboBox1.ValueMember = Batch No; comboBox1.DisplayMember = BatchID;

vinod jangir · Answer

Object reference not set to an instance of an object. i got this error

Manas Mohapatra · Answer

Please comment below lines: //DataRow dr; //dr = dt.NewRow(); //dr.ItemArray = new object [] { 0 ---Select an item--- }; //dt.Rows.InsertAt(dr 0);

vinod jangir · Answer

input array is longer than the number of columns in this table error found

Manas Mohapatra · Answer

Try below code: da.Fill(dt); DataRow dr; dr = dt.NewRow(); dr.ItemArray = new object [] { 0 ---Select an item--- }; dt.Rows.InsertAt(dr 0); comboBox1.DisplayMember =  Batch No  ; comboBox1.ValueMember =  Batch No  ; comboBox1.DataSource = dt; Here I added DisplayMember ValueMember as Batch No. You can change per your requirement.