Rotate columns to rows for joined tables - sql

Question

I have two tables similar to shown below (just leaving out fields for simplicity).
Table lead :
id | fname | lname | email
---------------------------------------------
1 | John | Doe | jd#test.com
2 | Mike | Johnson | mj#test.com
Table leadcustom :
id | leadid | name | value
-------------------------------------------------
1 | 1 | utm_medium | cpc
2 | 1 | utm_term | fall
3 | 1 | subject | business
4 | 2 | utm_medium | display
5 | 2 | utm_term | summer
6 | 2 | month | may
7 | 2 | color | red
I have a database that captures leads for a wide variety of forms that often have many different form fields. The first table gets the basic info that I know is on each form. The second table captures all other forms fields that were sent over so it can really contain a lot of different fields.
What I am trying to do is to do a join where I can grab all fields from lead table along with utm_medium and utm_term from leadcustom table. I don't need any additional fields even if they were sent over.
Desired results :
id | fname | lname | email | utm_medium | utm_term
---------------------------------------------------------------------------
1 | John | Doe | jd#test.com | cpc | fall
2 | Mike | Johnson | mj#test.com | display | summer
Only way I know I could do this is to grab all lead data and then for each record make more calls to get leadcustom data I am looking for but I know there has to me a more efficient way of getting this data.
I appreciate any help with this and it is not something I can change the way I capture that data and table formats.

Answer 1

If your columns are fixed, you can do this with group by + case + max like this:
select
fname,
lname,
email,
max(case when name = 'utm_medium' then value end) as utm_medium,
max(case when name = 'utm_term' then value end) as utm_term
from
lead l
join leadcustom c
on l.id = c.leadid
group by
fname,
lname,
email
The case will assign value from the leadcustom table when it matches the given name, otherwise it will return null, and max will pick take the assigned value if it exists over the null.
You can test this in SQL Fiddle
The other way to do this is to use pivot operator, but that syntax is slightly more complex -- or at least this is more easy for me.

Answer 2

Unless I interpret your question incorrectly - in which case I'm happy to be corrected - you could achieve your goal with a simple left join where you join on ID of the first table:
select ld.*, ldcust.utm_medium, ldcust.utm_term
from lead ld
left join leadcustom ldcust
on ld.id = ldcust.leadid

Answer 3

You can use a cte or a derived table to solve this:
cte:
;with cte as
(
select leadid, [name], [value]
from leadcustom
where name in('utm_medium', 'display')
)
select id, fname, lname, email, [name], [value]
from lead
inner join cte on(id = leadid)
Derived table:
select id, fname, lname, email, [name], [value]
from lead
inner join
(
select leadid, [name], [value]
from leadcustom
where name in('utm_medium', 'display')
) derived on(id = leadid)
and since suslov used JamesZ's fiddle, I will use it too...

Answer 4

declare #t table (Id int,fname varchar(10),lname varchar(10),email varchar(20))
insert into #t(Id,fname,lname,email)values (1,'john','doe','jd#test.com'),(2,'mike','johnson','mj#test.com')
declare #tt table (id int,leadid int,name varchar(10),value varchar(10))
insert into #tt(id,leadid,name,value)values
(1,1,'utm_medium','cpc'),
(2,1,'utm_term','fall'),
(3,1,'subject','business'),
(4,2,'utm_medium','display'),
(5,2,'utm_term','summer'),
(6,2,'month','may'),(7,2,'color','red')
select Id,fname,lname,
email,
[utm_medium],
[utm_term]
from (
select t.Id,
t.fname,
t.lname,
t.email,
tt.name,
tt.value
from #t t JOIN #tt tt
ON t.Id = tt.leadid)R
PIVOT(MAX(value) for name IN([utm_medium],[utm_term]))P

Answer 5

You can try with pivot and join:
select [id]
, [fname]
, [lname]
, [email]
, [utm_medium]
, [utm_term]
from ( select t2.*
, t1.[name]
, t1.[value]
from [leadcustom] t1
join [lead] t2 on t2.[id] = t1.[leadid]
) t
pivot (
max([value])
for [name] in ([utm_medium], [utm_term])
) pt
pivot rotates the joined table-valued expression, by turning the unique values from [value] column in the expression into [utm_medium] and [utm_term] columns in the output, and performs fake aggregation with max function (it works so because a corresponding column can have multiple values for one unique pivoted column, in this case, [name] for [value]).
SQLFiddle