SQL group table by user with custom column on same row - sql

Question

I have 3 tables
PATIENT:
patientid name comment result
--------------------------------
1 davis test p
2 brown test p
3 mike test p
PHONE TYPE:
phone_id patient_id phone_type
-------------------------------
3324 1 1
3325 1 4
5467 2 1
PHONE DETAILS:
phone_id number
-----------------------
3324 8253322
3325 180040204
5467 5674543
The goal is to add a column on the select statement based on the value of phone type (1 = phone, 4 = fax) and to group the column so that the phone and
fax are on the same line, not alternating.
Desired result:
name phone fax comment result
---------------------------------------------
davis 8253322 180040204 test p
brown 5674543 null test p
mike null null test p
I have this so far
select
a.name, a.comment, a.result,
(CASE WHEN (b.phone_type = 1) THEN c.number ELSE NULL END) AS Phone
(CASE WHEN (b.phone_type = 4) THEN c.number ELSE NULL END) AS Fax
The problem with this is that it doesn't group the values by the user.
name phone fax comment result
-----------------------------------------------
davis 8253322 null test p
davis null 180040204 test p
mike null null test p

Answer 1

If we can assume 1 phone/fax per name.
select a.name
, a.comment
, a.result
, max(CASE WHEN (b.phone_type = 1) THEN c.number ELSE NULL END) AS Phone
, max((CASE WHEN (b.phone_type = 4) THEN c.number ELSE NULL END) AS Fax
FROM...
GROUP BY a.name
, a.comment
, a.result
If not... then break phone and fax into two data sets based the type and generate row number for each set. Then use a full outer join on patentId and that row number.
With Phone as (SELECT phone_id, patient_id, phone_type, PD.Number, row_number() over (partition by Patient_ID order by PD.Number) as RN
FROM Phone_type PT
INNER JOIN Phone_Details PD
ON PT.Phone_ID = PD.Phone_ID
WHERE Phone_Type = 1),
Fax as (SELECT phone_id, patient_id, phone_type, PD.Number, row_number() over (partition by Patient_ID order by PD.Number) as RN
FROM Phone_type PT
INNER JOIN Phone_Details PD
ON PT.Phone_ID = PD.Phone_ID
WHERE Phone_Type = 1)
SELECT *
FROM PHONE P
FULL OUTER JOIN FAX F
on P.Patent_Id =F.PatentID
and P.RN=F.RN

Answer 2

You can use an aggregation function if you are sure you will only ever have one value at most for phone or fax.
select a.name, a.comment, a.result,
Min((CASE WHEN (b.phone_type = 1) THEN c.number ELSE NULL END) AS Phone,
Min((CASE WHEN (b.phone_type = 4) THEN c.number ELSE NULL END)) AS Fax
FROM (...)
GROUP BY a.name, a.comment, a.result

Answer 3

You can use the following SQL statement
WITH patient_phone AS (
SELECT a.name,
a.comment,
a.result,
(CASE WHEN (b.phone_type = 1) THEN c.number ELSE NULL END) AS Phone,
(CASE WHEN (b.phone_type = 4) THEN c.number ELSE NULL END) AS Fax
FROM patient a
LEFT OUTER JOIN phone_type b
ON a.patient_id = b.patient_id
LEFT OUTER JOIN phone_details c
ON b.phone_id = c.phone_id
GROUP BY a.name,
a.comment,
a.result,
b.phone_type,
c.number
)
SELECT name,
MAX(phone) phone,
MAX(fax) fax,
comment,
result
FROM patient_phone
GROUP BY name,
comment,
result
Result
name phone fax comment result
brown 5674543 NULL test p
davis 8253322 180040204 test p
mike NULL NULL test p