User Friends, best way to do it?

[imperium2335]

Hi,

 

I am making something where users have profiles and they can add friends.

 

The problem I am having is how to design my database for this, as one user can have many friends and all those friends can have many friends.

 

I know many to many relationships are discouraged but is that the only way this can be done?

 

I am thinking of having a column against each user where the ids of the users the user is friends with are listed i.e.

userId

userFriendIds

2

1, 13, 15, 63, 106, 253

 

So in my PHP to return all the friends of user 2, it would pull that big list of ids from the database and if stristr is true then they are friends.

 

What are your thoughts?

[imperium2335]

P.S

 

I just thought it could be done in a different table called something like 'friendships'.

 

e.g.

userId

friendId

1

25

1

207

1

99

2

31

2

207

7

1

 

Or is this way much more inefficient, btw speed is the most important thing for me, diskspace is irrelevant.

[requinix]

I just thought it could be done in a different table called something like 'friendships'.

That's the correct method.

[imperium2335]

Thanks, when it comes to indexing ive set the userid to be the primary key, would it be worth making friendid an index for performance gains?

 

It is likely that this table will experience a lot of updates.