MS SQL SERVER pivot table aggregation function - sql-server

Question

I have a question about the application of the aggregation function that used in pivot function.
The table OCCUPATIONS looks like this:
+-----------+------------+
| Name | Occupation |
+-----------+------------+
| Ashley | Professor |
| Samantha | Actor |
| Julia | Doctor |
| Britney | Professor |
| Maria | Professor |
| Meera | Professor |
| Priya | Doctor |
| Priyanka | Professor |
| Jennifer | Actor |
| Ketty | Actor |
| Belvet | Professor |
| Naomi | Professor |
| Jane | Singer |
| Jenny | Singer |
| Kristeen | Singer |
| Christeen | Singer |
| Eve | Actor |
| Aamina | Doctor |
+-----------+------------+
The first column is name and second is occupation.
Now I want to make a pivot table that each column is one kind of occupation and name is sorted alphabetically and print NULL when no more names for an occupation.
The output should looks like this:
+--------+-----------+-----------+----------+
| Doctor | Professor | Singer | Actor |
+--------+-----------+-----------+----------+
| Aamina | Ashley | Christeen | Eve |
| Julia | Belvet | Jane | Jennifer |
| Priya | Britney | Jenny | Ketty |
| NULL | Maria | Kristeen | Samantha |
| NULL | Meera | NULL | NULL |
| NULL | Naomi | NULL | NULL |
| NULL | Priyanka | NULL | NULL |
+--------+-----------+-----------+----------+
Here the first column is Doctor, second is Professor, third is Singer and fourth is Actor. The code to generate result is
select [Doctor],[Professor],[Singer],[Actor] from (select o.Name,
o.Occupation, row_number() over(partition by o.Occupation order by
o.Name) id from OCCUPATIONS o) as src
pivot
(max(src.Name)
for src.Occupation in ([Doctor],[Professor],[Singer],[Actor])
) as m
But when I replace the table generated from here:
(select o.Name, o.Occupation, row_number() over(partition by o.Occupation order by o.Name) id from OCCUPATIONS o) as src' to 'OCCUPATIONS'
the result is like this:
Priya Priyanka Kristeen Samantha
I understand why this happens, because we take a MAX() in each group. However, in the previous result, I also use a MAX() function to generate NULL when there's no more names coming, it doesn't return a max value as my expected, instead it return every name.
My question is why this happens?
Thank you!

Answer 1

Here could be the source of issue:
row_number() over(partition by o.Occupation order by
o.Name) id from OCCUPATIONS o
The Row_Number here you are using is PARTITION BY o.Occupation, so in your PIVOT, it will pivot the records by the occupation group, which means the id is repeating. If you get rid of the PARTITION BY and just keep the Order by part, it should work.

Answer 2

Try this approach:
find the occupations with more people associated
generate table with a sequence of numbers from 1 to the number of people calculated in the previous point
join the table generated in point 2. four times with the original table each time filtering on a different Occupation
This is the query:
declare #tmp table([Name] varchar(50),[Occupation] varchar(50))
insert into #tmp values
('Ashley','Professor') ,('Samantha','Actor') ,('Julia','Doctor') ,('Britney','Professor') ,('Maria','Professor') ,('Meera','Professor') ,('Priya','Doctor') ,('Priyanka','Professor') ,('Jennifer','Actor') ,('Ketty','Actor') ,('Belvet','Professor') ,('Naomi','Professor') ,('Jane','Singer') ,('Jenny','Singer') ,('Kristeen','Singer') ,('Christeen','Singer') ,('Eve','Actor') ,('Aamina','Doctor')
--this variable contains the occuation that has more Names (rows) in the table
--it will be the number of total rows in output table
declare #Occupation_with_max_rows varchar(50)
--populate #Occupation_with_max_rows variable
select top 1 #Occupation_with_max_rows=Occupation
from #tmp
group by Occupation
order by count(*) desc
--generate final results joining 4 times the original table with the sequence table
select D.Name as Doctor,P.Name as Professor,S.Name as Singer,A.Name as Actor
from
(select ROW_NUMBER() OVER (ORDER BY [Name]) as ord from #tmp where Occupation = #Occupation_with_max_rows) O
left join
(select ROW_NUMBER() OVER (ORDER BY [Name]) as ord, [Name] from #tmp where Occupation='Doctor') D on O.ord = D.ord
left join
(select ROW_NUMBER() OVER (ORDER BY [Name]) as ord, [Name] from #tmp where Occupation='Professor') P on O.ord = P.ord
left join
(select ROW_NUMBER() OVER (ORDER BY [Name]) as ord, [Name] from #tmp where Occupation='Singer') S on O.ord = S.ord
left join
(select ROW_NUMBER() OVER (ORDER BY [Name]) as ord, [Name] from #tmp where Occupation='Actor') A on O.ord = A.ord
Results:

Answer 3

Please find below code which works as expected :
select [Doctor],[Professor],[Singer],[Actor]
from
(
select row_number() over (partition by occupation order by name)[A],name,occupation
from occupations
)src
pivot
(
max(Name)
for occupation in ([Doctor],[Professor],[Singer],[Actor])
)piv;