Wordpress - 使用'get_post'一次只选择两个指定猫中的帖子

I am trying to use 'get_posts' to pick up posts that are in two categories. Currently I am using this: $myposts = get_posts('numberposts=1&category=4&category=7');

This picks up posts that are either in category 4 or 7. The posts I want to pick up must be in both categories at once. Any suggestions?

Use this

$myposts = get_posts('numberposts=1&category=4,7');