Dynamic pivot table for every single row (MySql) - mysql

Question

I have a table Customers like:
ID Type Date Address SSN
RT124 MASTER 12/15/2005 7 Hill st 12345
RT542 MASTER 06/14/2006 7 Hill st 12345
HT457 UNIQUE 10/27/2009 10 PARK WAY 24569
QA987 UNIQUE 08/28/2010 10 PARK WAY 24569
AH825 UNIQUE 10/12/2012 10 PARK WAY 24569
14837 SINGLE 05/05/2010 2 TED ROAD 11111
24579 MARRIED 06/24/2014 2 TED ROAD 11111
What I want is to create a new column +# for every duplicate address and SSN and always the ID #1 should be the Date most recent.
Note: this table only has duplicate rows based on the address and SSN but unique ID and it doesn't require any sum.
So the output should be like this (Click on the image to zoom):
I have done some research and tried some examples but nothing work to get this output.
I will appreciate any help !

Answer 1

You need to enumerate the rows and aggregate. In MySQL (pre V8), it looks like:
select address, ssn,
max(case when rn = 1 then id end) as id1,
max(case when rn = 1 then type end) as type1,
max(case when rn = 1 then date end) as date1,
max(case when rn = 2 then id end) as id2,
max(case when rn = 2 then type end) as type2,
max(case when rn = 2 then date end) as date2
. . .
from (select c.*,
(#rn := if(#as = concat_ws(':', address, ssn), #rn + 1,
if(#as := concat_ws(':', address, ssn), 1, 1)
)
) as rn
from (select c.* from customers c order by address, ssn, date desc) c cross join
(select #as := '', #rn := 0) params
) c
group by address, ssn;
Note that this doesn't repeat address and ssn. That doesn't seem useful, but you can of course repeat those columns in each group.

Answer 2

Is there a limit to the number of times an address can be duplicated? If there is a known limit, you could have a number of left joins for each duplicate. The following would be a solution if you knew there would only ever be 6 or fewer duplicates:
with a as (
select
ID
,type
,date
,address
,SSN
row_number() over(partition by address, SSN order by date desc) as R
from Customers
)
select
a.id ID1
,a.type TYPE1
,a.date DATE1
,a.address ADDRESS1
,a.ssn SSN1
,b.id ID2
,b.type TYPE2
,b.date DATE2
,b.address ADDRESS2
,b.ssn SSN2
,c.id ID3
,c.type TYPE3
,c.date DATE3
,c.address ADDRESS3
,c.ssn SSN3
,d.id ID4
,d.type TYPE4
,d.date DATE4
,d.address ADDRESS4
,d.ssn SSN4
,e.id ID5
,e.type TYPE5
,e.date DATE5
,e.address ADDRESS5
,e.ssn SSN5
,f.id ID6
,f.type TYPE6
,f.date DATE6
,f.address ADDRESS6
,f.ssn SSN6
from a
left join
(select * from a
where r=2
) b
on a.address=b.address and a.ssn=b.ssn
left join
(select * from a
where r=3
) c
on a.address=c.address and a.ssn=c.ssn
left join
(select * from a
where r=4
) d
on a.address=d.address and a.ssn=d.ssn
left join
(select * from a
where r=5
) e
on a.address=e.address and a.ssn=e.ssn
left join
(select * from a
where r=6
) f
on a.address=f.address and a.ssn=f.ssn
where r=1
If you have more than 6, just add another set of columns to the select statement:
,f.id ID6
,f.type TYPE6
,f.date DATE6
,f.address ADDRESS6
,f.ssn SSN6
and a new left join to the from statement:
left join
(select * from a
where r=6
) f
on a.address=f.address and a.ssn=f.ssn