Take tables: User, Comment, Snippet.

A Person might have many Clips. A Snippet might have many Comments. A Person can leave many Comments.

Consequently, after i diagram things, I finish track of something similar to a triangular.

User 1-------------* Comment
      \           / 
       \         /
        *Snippet 1

Obviously a database might have associations like this:

Users
  id
  name
  address

Snippets
  id
  user_id
  body

Comments
  id
  body
  snippet_id
  user_id

Good examples:

--Get all comments by a user
SELECT * FROM comments WHERE user_id = 1

--Get all snippets by a user
SELECT * FROM snippets WHERE user_id = 1

--Get all comments on a snippet
SELECT * FROM comments WHERE snippet_id = 1

--Get all comments on a particular snippet by a particular user
SELECT * FROM comments WHERE snippet_id = 1 AND user_id = 1

Absolutely.

create table Users (Id int not null primary key identity(1,1))
create table Snippets (Id int not null primary key identity(1,1), 
                       UserId int not null)
create table Comments (Id int not null primary key identity(1,1),
                       SnippetId int not null,
                       UserId int not null)

Setup your foreign secrets and you are ready.