如何通过自定义字段日期来订购wordpress文章?

I am making an event sidebar section that will only display the next 3 events. I have got the custom post type and custom fields all working but I can seem to figure out how to order the posts by the start date of the events, which is a custom field value. Is there a php function that can compare dates and organize them into a certain order. I think it would also have to hold the post-id with the newly arranged dates so that when I read through the values, i can display the appropriate post with that date.I am making an event sidebar section that will