C#(Windows Forms): How to get the MAX column value from a database table (SQL)
I have a table named invoicedetails in my database.
I have to get the max value of the invoiceNo column and display it after incremented that value by 1. I searched hours on the net and found several solutions. This is what I tried,
(no problem with the connection)
string connectionString = "path";
SqlConnection con;
con = new SqlConnection(connectionString);
con.Open();
SqlCommand cmd = new SqlCommand();
String query = "Select max(invoiceNo) from invoicedetails";
cmd.Connection = con;
cmd.CommandText = query;
int invNo = Convert.ToInt32(cmd.ExecuteScalar());
int newInv=invNo + 1;
textBoxInvoiceNo.Text = newInv.ToString();
I have put this code to the form load event. But the InvoiceNo text box displays nothing. And this
exception displays:-"Object cannot be cast fromDBNull to other types".
Where's the problem?
I have to get the max value of the invoiceNo column and display it after incremented that value by 1. I searched hours on the net and found several solutions. This is what I tried,
(no problem with the connection)
string connectionString = "path";
SqlConnection con;
con = new SqlConnection(connectionString);
con.Open();
SqlCommand cmd = new SqlCommand();
String query = "Select max(invoiceNo) from invoicedetails";
cmd.Connection = con;
cmd.CommandText = query;
int invNo = Convert.ToInt32(cmd.ExecuteScalar());
int newInv=invNo + 1;
textBoxInvoiceNo.Text = newInv.ToString();
I have put this code to the form load event. But the InvoiceNo text box displays nothing. And this
exception displays:-"Object cannot be cast fromDBNull to other types".
Where's the problem?
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