Select multiple rows into columns - dynamic pivot - sql

Question

Here is what the initial query returns:
plan_id Rep_id rep_nm employee_id Row_id
6720 35 Robert Jones 160 1
6720 36 Pam Smith 23 2
6720 37 Erik Johnson 85 3
6720 38 Sally Ells 212 4
6719 40 Barbara Wax 168 5
I need to get the rows to be as follows:
plan_id Rep_id1 rep_nm1 emp_id1 Rep_id2 rep_nm2 emp_id2 Rep_id3 etc.
6720 35 Robert Jones 160 36 Pam Smith 23 Erik Johnson
6719 40 Barbara Wax 168 NULL NULL NULL NULL
The maximum rep_id* columns will be 5. I tried searching for a pivot query for such an example but no success.

Answer 1

You did not specify what RDBMS you are using but if you are using SQL server, then you can implement both the UNPIVOT and PIVOT functions. If you know how many values you are going then you can hard-code the values:
select *
from
(
select plan_id, value, col+cast(rn as varchar(10)) col
from
(
select plan_id,
cast(rep_id as varchar(12)) rep_id,
rep_nm,
cast(employee_id as varchar(12)) employee_id,
row_number() over(partition by plan_id order by rep_id) rn
from yourtable
) src
unpivot
(
value
for col in (rep_id, rep_nm, employee_id)
) up
) un
pivot
(
max(value)
for col in ([rep_id1], [rep_nm1], [employee_id1],
[rep_id2], [rep_nm2], [employee_id2],
[rep_id3], [rep_nm3], [employee_id3],
[rep_id4], [rep_nm4], [employee_id4])
) piv
See SQL Fiddle with Demo
But if you have an unknown number of values, then you can use dynamic SQL similar to this:
DECLARE #colsUnpivot AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX),
#colsPivot as NVARCHAR(MAX)
select #colsUnpivot = stuff((select ','+quotename(C.name)
from sys.columns as C
where C.object_id = object_id('yourtable') and
C.name not in ('plan_id', 'Rep_id', 'Row_id')
for xml path('')), 1, 1, '')
select #colsPivot = STUFF((SELECT ','
+ quotename(c.name
+ cast(t.rn as varchar(10)))
from
(
select row_number() over(partition by plan_id order by rep_id) rn
from yourtable
) t
cross apply sys.columns as C
where C.object_id = object_id('yourtable') and
C.name not in ('plan_id', 'Rep_id', 'Row_id')
group by c.name, t.rn
order by t.rn
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query
= 'select *
from
(
select plan_id, value, col+cast(rn as varchar(10)) col
from
(
select plan_id,
cast(rep_id as varchar(12)) rep_id,
rep_nm,
cast(employee_id as varchar(12)) employee_id,
row_number() over(partition by plan_id order by rep_id) rn
from yourtable
) x
unpivot
(
value
for col in ('+ #colsunpivot +')
) u
) src
pivot
(
max(value)
for col in ('+ #colspivot +')
) p'
exec(#query)
See SQL Fiddle with Demo
Both will produce the same result:
| PLAN_ID | EMPLOYEE_ID1 | REP_NM1 | EMPLOYEE_ID2 | REP_NM2 | EMPLOYEE_ID3 | REP_NM3 | EMPLOYEE_ID4 | REP_NM4 |
------------------------------------------------------------------------------------------------------------------------------
| 6719 | 168 | Barbara Wax | (null) | (null) | (null) | (null) | (null) | (null) |
| 6720 | 160 | Robert Jones | 23 | Pam Smith | 85 | Erik Johnson | 212 | Sally Ells |