Don't do this.
1 - You should separate markup and presentational elements using CSS
2 - If you want to apply a border later then you'll have to edit the HTML instead of making a simple change in CSS
3 - The question was about applying a border so how would border="0" help?
However, what Tommy said is correct so you may have something else wrong with your code?
border: 1px solid #000000;
<th scope="col">table head 1</th>
<th scope="col">table head 2</th>
<td>table data 1</td>
<td>table data 2</td>
<td>table data 3</td>
<td>table data 4</td>
Also, Tyssen's advice will be applicable if you decide that you want borders on your tr's or td's as there will be a margin between the cells by default unless you collapse them.