Question

+-----------------------------------+
| fID | personA | personB | fStatus |
|-----------------------------------|
|  1  |  u1ID   |   u2ID  |    1    |
|  2  |  u3ID   |   u4ID  |    0    |
|  3  |  u1ID   |   u3ID  |    1    |
+-----------------------------------+

Status Column Codes:
0: Pending (personA wants to be friends with personB)
1: Friends (personA with personB)

* On removal request by either side > delete the corresponding row

I want to have a simple MySQL table by which I could implement a friendship option on my website. Being friends or not is all it needs to possess.

Now I want to know about the best approach for this purpose, and if there is something that I’m missing. I want to query friends of each user and users should be able to add or remove each other from their friend-list(s).

Answer 1

Since each person could be friend with another person, you need to implement a NxM (many to many) relation. That translates, in a relational database managemen systemt, in another table, to make the “junction”, just as you did.

http://weblogs.asp.net/zeeshanhirani/archive/2008/08/21/many-to-many-mappings-in-entity-framework.aspx

In you example, maybe you may want to add a column to know who asked the friendship to who else.

edit: I would maybe remove the fId column and create a composed primary key of the columns (foreign keys) personA and personB. This way it will be avoided by the db to have more than one request for the same persons, and also to avoid a situation where personA ask friendship to personB and personB, instead of just accepting it, asks friendship to personA, resulting in two records!

edit2: you could use the status field to store the friendship request “owner”:

0: pending, A asked to B
1: pending, B asked to A
2: friends

edit3: don’t you need an expiration time (column request_date)? if a friendship request is not answered in, say, 3 months, then the request expires and it is deleted.