Concatenate values with LEFT join - mysql

Question

While searching, I came across a very similar post here
but I have an additional question to what has been posted there already.
id|person_name|department_name|phone_number
--+-----------+---------------+------------
1 |"John" |"Finance" |"023451"
1 |"John" |"Finance" |"99478"
1 |"John" |"Finance" |"67890"
1 |"John" |"Marketing" |"023451"
1 |"John" |"Marketing" |"99478"
1 |"John" |"Marketing" |"67890"
2 |"Barbara" |"Finance" |""
3 |"Michelle" |"" |"005634"
Lets say I want the final result as:
id|person_name|department_name|phone_number
--+-----------+---------------+------------
1 |"John" |"Finance" |"023451", "99478", "67890"
1 |"John" |"Marketing" |"023451", "99478", "67890"
2 |"Barbara" |"Finance" |""
3 |"Michelle" |"" |"005634"
basically similar results from phone_number concatenated; then can you advise what should I be doing ? I tried GROUP_CONCAT with DISTINCT but it didn't help.

Answer 1

So this will pivot and comma delimit your Numbers which I believe is the desired effect? This is a SQL Server solution
declare #t table (OrderedID int, EmpName varchar(50), EmpDep varchar(50), Num varchar(50))
insert into #t
values
(1,'John','Dep1','123')
,(1,'John','Dep1','456')
,(1,'John','Dep2','789')
,(2,'Doug','Dep1','987')
,(2,'Doug','Dep1','654')
,(2,'Steve','Dep2','321')
Select
*
From #t
SELECT distinct e.EmpName,
e.EmpDep,
LEFT(r.Num , LEN(r.Num)-1) num
FROM #t e
CROSS APPLY
(
SELECT r.Num + ', '
FROM #t r
where e.EmpName = r.EmpName
and e.EmpDep = r.EmpDep
FOR XML PATH('')
) r (Num)
Ouput:
EmpName EmpDep num
Doug Dep1 987, 654
John Dep1 123, 456
John Dep2 789
Steve Dep2 321