在phpmyadmin数据库设计器中建立关系有什么意义？

Question

I understand some basics about relational database. But I don't get the point of making relation through phpmyadmin designer. What is the benefit there when I have to query any related table with another table's content ID?

When I make any query to select post where user_id=1, is there any way to make it like that, I will select from user_list where id=1, and I don't have to make another query to table posts?

Answer 1

To answer the first question: It documents the relationships for reference, and most designer applications will generate constraints enforcing those relationships.

To your answer your second question, no. If you only want information from posts, there would be no reason to involve users_list unless it relied on information from there, such as wanting to know "posts made by any users with the first name 'bob'"; in which case you would use a join. But if you already know the id for the user, there is no reason to involve users_list.