SRPSnippet1.cs

using (var sqlConnection = new SqlConnection(connectionString))
{
    sqlConnection.Open();

    try
    {
        using (var readCommand = new SqlCommand("select * from Entity", sqlConnection))
        {
            var reader = readCommand.ExecuteReader();

            while (reader.Read())
            {
                currenValue = reader.GetInt32(0);
                type = reader.GetInt32(1);
            }

            reader.Close();
        }

        using (var updateCommand = new SqlCommand(String.Format("update Entity set Data = {0} where Data = {1}", newValue, currenValue), sqlConnection))
        {
            updateCommand.ExecuteNonQuery();
        }

        Console.WriteLine("Data successfuly modified!");
        Console.ReadLine();
    }
    catch(Exception e)
    {
        Console.WriteLine("Failed to modify data");
    }
}