public bool login(string unamePI, string passPI)
    {
        DataTable mytable = new DataTable();
        bool mydeger = false;
        mytable = GetTableWithQueryParams("select * from UYE where USERNAME ={0} and PASSWORD={1}", unamePI, passPI);

        if (mytable.Rows.Count > 0)
        {
            mydeger = true;
        }
        else
        {
            return mydeger;
        }
        string de = mytable.Rows[0].ToString();
        return mydeger; }

public static DataTable GetTableWithQueryParams(string SQLCommandText, params object[] myParametres)
        {
            string aConnectionString = "Data Source = ..; Initial Catalog = mydatabase; Persist Security Info = True; User ID = ..; Password = ..";
            SqlConnection SqlConn = new SqlConnection(aConnectionString);
            SqlCommand MyCommand = new SqlCommand("", SqlConn);
            DataTable MyTable = new DataTable();

            try
            {
                int i = 0;
                SqlConn.Open();
                foreach (object MyObject in myParametres)
                {
                    if (SQLCommandText.Contains("{" + i.ToString() + "}"))
                    {
                        SQLCommandText = SQLCommandText.Replace("{" + i.ToString() + "}", "@Prm" + i.ToString());
                        MyCommand.Parameters.AddWithValue("Prm" + i.ToString(), MyObject);
                        i++;
                    }
                }
                MyCommand.CommandText = SQLCommandText;
                SqlDataReader MyReader = MyCommand.ExecuteReader();
                MyTable.Load(MyReader);
                SqlConn.Close();
                MyReader.Dispose();
            }
            catch (Exception ex)
            {
                throw new Exception(SQLCommandText + "n" + ex.Message);
            }
            finally
            {
                SqlConn.Dispose();
                MyCommand.Dispose();
            }
            return MyTable;
        }