INNER or LEFT Joining Multiple Table Records Into A Single Row

Question

Phone Table

+----------------+-------------+
| Field          | Type        |
+----------------+-------------+
| f_id           | int(15)     |
|         


        

Answer 1

Are there limits on how many Work or Home numbers a particular Client record can have? If it can be many, then no, there is no way to make a single row. If there can be at most 1 of each, then you can just join on the phone numbers table twice.

Answer 2

Though you can join several numbers (in any) into a single field:

SELECT
  CONCAT(f_first_name, ' ', f_last_name) as Client_Name,
  GROUP_CONCAT(IF(phone_type='work',f_phone_number, NULL)) as Work_Numbers,
  GROUP_CONCAT(IF(phone_type='home',f_phone_number, NULL)) as Home_Numbers
FROM clients
JOIN phone
  USING (f_id)
WHERE phone_type IN ('home', 'work')
GROUP BY f_id;

Answer 3

SELECT CONCAT(c.f_first_name, ' ', c.f_last_name) as Client_Name, 
       wp.f_phone_number as Work_Number,
       hp.f_phone_number as Home_Number

  FROM clients c
       LEFT OUTER JOIN phone hp
       ON hp.f_client_id = c.f_id
    AND
       hp.phone_type = 'home'
       LEFT OUTER JOIN phone wp
       ON wp.f_client_id = c.f_id
    AND
       wp.phone_type = 'work'

With LEFT OUTER JOINs you will still get rows for clients with missing numbers. If you don't want to see those, change to INNER JOINs.

Edit: As Nick kindly reminds me, this will return multiple rows for clients with multiple phone numbers. Once you have the data you need, you're then faced with presentation issue. You can handle that in the application layer, or make a sacrifice to the SQL gods and look into MySQL's GROUP_CONCAT() function.