string cnString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirector  y|\SELLPC.mdf;Integrated Security=True;User Instance=True";
SqlConnection cn = new SqlConnection(cnString);
DataSet dataset = new DataSet();
string query = "SELECT * FROM TBLCPU ";
SqlDataAdapter datada = new SqlDataAdapter(query, cn);
datada.Fill(dataset, "TBLCPU");
for (int i = 1; i <= dataset.Tables["TBLCPU"].Rows.Count; i++)
{
string str=(string)(dataset.Tables["TBLCPU"].Rows[i - 1]["MDLCPU "]);
if (str.Contains(cmbmdlcpu.Text))
txtprccpu.Text = (string)(dataset.Tables["TBLCPU"].Rows[i - 1]["heads"]);
}