Question

I have a table with 3 fields. principal, associate, status.

How can I determine whether the logged-in user is either a principal or an associate, and with how many people he is associated? I would also like to determine the status of the relationship.

query = "SELECT M.id, M.surname, M.firstname, R.principal_id
         , R.associate_id, R.status 
         FROM tbl_members M, tbl_relationship R WHERE
         -- ---------------------------------------------
         -- to make sure user exists in the members table
         -- ---------------------------------------------
         (R.principal_id = M.id OR R.associate_id = M.id) 
         AND (logged-in-user = R.associate_id OR logged-in-user = R.principal_id)
         AND R.status =1"

ERROR:- THIS LISTS times 2 of everybody in the relationship table.

Tables invloved:-
tbl_members (id, surname, firstname)
tbl_relationship (id, associate_id[FK tbl_member id], principal_id[FK tbl_member id])

associate_id | principal_id | status

1 3 1
1 4 1
2 1 0
2 3 0
5 1 1
6 1 1

From the above how many people are associated with logged-in-user(1)?

Answer 1

Try:

SELECT
      m.id, m.surname, m.firstname,
      COUNT(assoc.id) AS relationships_as_associate, 
      COUNT(princ.id) AS relationships_as_principal
FROM tbl_members m
     LEFT JOIN tbl_relationship assoc 
          ON assoc.associate_id = m.id AND assoc.status = 1
     LEFT JOIN tbl_relationship princ 
          ON princ.principal_id = m.id AND princ.status = 1
WHERE m.id = logged-in-user
GROUP BY m.id

(guessing that relationships with status = 0 can be ignored)

If you only want the number of relationships this user is in (no matter the user’s role):

SELECT
      m.id, m.surname, m.firstname,
      COUNT(rel.id) AS active_relationships
FROM tbl_members m
     LEFT JOIN tbl_relationship rel
          ON (rel.associate_id = m.id OR rel.principal_id = m.id)
          AND rel.status = 1
WHERE m.id = logged-in-user
GROUP BY m.id

EDIT:

According to your comment, this is a query that will get all the users who are in relationship with the logged in user, with their details, and the role they are playing in the relationship (some of them are principals, others are associates):

SELECT m.id, m.firstname, m.surname, temp.role
FROM tbl_members m
JOIN ((SELECT rel.principal_id as id, 'Principal' as role
       FROM tbl_relationship rel
       WHERE rel.associate_id = logged-in-user
       AND rel.status = 1)
     UNION
      (SELECT rel.associate_id as id, 'Associate' as role
       FROM tbl_relationship rel
       WHERE rel.principal_id = logged-in-user
       AND rel.status = 1)
     ) as temp
ON temp.id = m.id