Q: Sql Relative DB username I have two tables:
user [id, username]
comment [title, content, postid, userid]
my backend is nodejs...
how can i query all comments and not get the id, but the username in the result?
Select * from comments where postid=1

In this case, i'll get the userid in the result
Do i need a relative db?

A: use join 
select username,title,content from user  u join comments c on u.id=c.userid

