Check if Dataset is Null?

Janis,

You are accessing ds before you have filled it (only new DataSet() has been executed so that ds does not equal null at the moment).

You should do dscmd.Fill(ds); before line if (ds != null). However, dscmd.Fill(ds) must be enclosed into a try...catch block so that you can handle exceptions caused by bad query for example. So basically your code might look like this:

using (...)
{

    Acces2.Open();
    OleDbDataAdapter dscmd = new OleDbDataAdapter("SELECT id2, atvk, atvk_nos, adrese, uzvards, vards, dzim_date, reize, nedela, [no], lidz, telefons AS telef FROM " + value3 + "man", Acces2);
    DataSet ds = new DataSet();

    try
    {
        dscmd.Fill(ds);
    }
    catch (System.Exception ex)
    {
        // report ex in any way applicable
        ds = null;    // this indicates that there was an error filling the dataset
    }

    if (ds != null)
    {
        dataGridView1.DataSource = ds.Tables[0];
        ...
    }
   
    ...
   
}