auto increment billno and print it on textbox

Question

public void billno() { SqlCommand cmd = new SqlCommand("select count(billno) from saletable", con); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); if(dt.Rows.Count>0) { } }

Jenith Thakkar · Answer

Okay you want to show next bill no right?

Amit Gupta · Answer

select ISNULL(MAX(ISNULL(billno,0)))+1 from tableName

Jenith Thakkar · Answer

I think there's no need to use data table Please try this SqlCommand cmd = new SqlCommand("select MAX(billno) as billno from saletable", con); int billno = Convert.ToInt32(cmd.ExecuteScalar()); int res= billno+1; txtbill.Text = Convert.ToString(res); txtbill.Text = "";

Anvar S · Answer

still not working . showing this error Object cannot be cast from DBNull to other types.

Jenith Thakkar · Answer

Okay Try this SqlCommand cmd = new SqlCommand("select MAX(billno) as billno from saletable", con); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); if(dt.Rows.Count>0) { //int billnum = 0; int billno = Convert.ToInt32(dt.Rows[0][0]); int res = billno+1 ; txtbill.Text = Convert.ToString(res); txtbill.Text = ""; } }

Anvar S · Answer

yes sir

Anvar S · Answer

hello sir i have table saletable which has field id that i set to autoincrement,billno which is not auto increment. i want to display the billno on textbox each time i load the form.i am stuck with here. protected void Page_Load(object sender, EventArgs e) { con.Open(); grid(); if (!IsPostBack) { billno(); } } public void billno() { SqlCommand cmd = new SqlCommand("select count(billno) from saletable", con); SqlDataAdapter da = new SqlDataAdapter(cmd); DataTable dt = new DataTable(); da.Fill(dt); if(dt.Rows.Count>0) { //int billnum = 0; int billno = Convert.ToInt32(dt.Rows[0][0]); int res = billno+1 ; txtbill.Text = Convert.ToString(res); txtbill.Text = ""; } }

Jenith Thakkar · Answer

Please Update your issue in detail