move server, all pages template become default

I have many pages and create many template. some for home page, some for blog, some for articles…
But when I move server(copy all the files include mysql files), I find all the page become default template(in back page page edit), I checked the database wp_posts, there have no field to store page template, So is it a BUG? or how to handle it>

Many thx.
Yuli Chika