select the maximum value, and automatically generate the Product Code.

Question

Hello everyone

 

I am trying to select the maximum value, and automatically generate the Product Code.

 

This is the Code, but it doesn't come out.

try
{
    using(var Conexion = new SqlConnection(VariablesGlobales.CadenaConexion))
    {
        Conexion.Open();
        string consultaSQL = "select Max(CodigoProducto) As maximo FROM TblaProducto2";
        var comando = new SqlCommand(consultaSQL, Conexion);
        SqlDataReader LD = comando.ExecuteReader();
        if(LD.Read() == true)
            if(maximo = 0)
            {
                txtCodigo1.Text = "1";
            }
            else
            {
                maximo = maximo + 1;
                txtCodigo1.Text = maximo;
            }
            {}
    }
}
catch(Exception ex) //
{
    MessageBox.Show("Error al intentar seleccionar el valor maximo");
    MessageBox.Show(ex.Message); // Muestra el Mensaje de Error.            
}

I count on your help

Answer 1

Is this what you're after?:

LD.Read();

var max = reader.GetInt32(3);

txtCodingo1.Text = max + 1;

Disclaimer: it's normally better to let SQL decide new IDs with an auto-incrementing ID column:

https://www.w3schools.com/sql/sql_autoincrement.asp

This avoids inevitable race conditions, particularly if this is a multi-user app.

Answer 2

Also be sure not to use this code in a multiple user environment, as you could get duplicate product codes.

If used in a multiple user environment, be sure the first save of the product code is to unique column, and catch the duplicate key error. This will tell your code it needs to generate a new key.

Answer 3

solved 100x%

I was able to autonumber it in the database.

thank you...