Consulta sql com or?

[SrMaster]

Como coloco um or?

<?php

$sql = "select * from noticias where categoria_id = 1 order by id DESC limit 2";

$query = mysql_query($sql);

while($linha = mysql_fetch_array($query)) {

$autor_id = $linha["autor_id"];

$cat_id = $linha["categoria_id"];

?>

tipo: $sql = "select * from noticias where categoria_id = 1 or 2 order by id DESC limit 2";

[ESerra]

categoria_id = 1 OR categoria_id = 2