merge rows in a sql query and create additional columns for different information - sql

Question

I have a sql query that is returning a number of customer results.
each customer has a unique ID but may have multiple transactions.
instead of having multiple rows for each customer i would like to have one row and generate multiple columns for the different info.
for example i have:
id | name | purchase price | date
3 | tim | 20 | 08-2-2014
3 | tim | 25 | 08-5-2014
and i want it to read
id | name | purchase price 1 | date 1 | purchase price 2 | date 2
3 | tim | 20 | 08-2-2014 | 25 | 08-5-2014
I have no idea where to start.

Answer 1

This is done using a dynamic cross tab.
For reference: http://www.sqlservercentral.com/articles/Crosstab/65048/
-- build sample data
create table #temp_table(
id int,
name varchar(255),
[purchase price] decimal(10,2),
[date] smalldatetime
)
insert into #temp_table
select 3, 'tim', 20, '20140802' union all
select 3, 'tim', 25, '20140805' union all
select 4, 'joe', 25, '20140801' union all
select 4, 'joe', 25, '20140803' union all
select 4, 'joe', 25, '20140807' union all
select 1, 'bob', 25, '20140811'
declare #sql1 varchar(4000)
declare #sql2 varchar(4000)
declare #sql3 varchar(4000)
declare #max int
declare #counter int
select #counter = 1
select top 1 #max = count(*) from #temp_table group by id order by count(*) desc-- get number of columns
select #sql1 =
'select
id,
name,
'
select #sql3 =
'from(
select
*,
rn = row_number() over(partition by id, name order by [date])
from #temp_table
)t
group by id, name
order by id'
select #sql2 = ''
while #counter <= #max begin
select #sql2 =
#sql2
+ ' max(case when rn = ' + convert(varchar(10),#counter) + ' then [purchase price] else null end) as [purchase price ' + convert(varchar(10),#counter) + '],' + char(10)
+ ' max(case when rn = ' + convert(varchar(10),#counter) + ' then [date] else null end) as [date ' + convert(varchar(10),#counter) + ']'
if #counter <> #max begin
select #sql2 = #sql2 + ','
end
select #sql2 = #sql2 + char(10)
select #counter = #counter + 1
end
print (#sql1 + #sql2 + #sql3)
exec (#sql1 + #sql2 + #sql3)
drop table #temp_table
Sample Data:
id name purchase price date
----------------------------------------
3 tim 20.00 2014-08-02 00:00:00
3 tim 25.00 2014-08-05 00:00:00
4 joe 25.00 2014-08-01 00:00:00
4 joe 25.00 2014-08-03 00:00:00
4 joe 25.00 2014-08-07 00:00:00
1 bob 25.00 2014-08-11 00:00:00
Result:
id name purchase price 1 date 1 purchase price 2 date 2 purchase price 3 date 3
--------------------------------------------------------------------------------------------------------------------------------------------
1 bob 25.00 2014-08-11 00:00:00 NULL NULL NULL NULL
3 tim 20.00 2014-08-02 00:00:00 25.00 2014-08-05 00:00:00 NULL NULL
4 joe 25.00 2014-08-01 00:00:00 25.00 2014-08-03 00:00:00 25.00 2014-08-07 00:00:00