Dynamic Pivot Tables MS SQL 2008 - sql-server

Question

I'm trying to create a dynamic pivot table to get results in different columns rather than rows.
This is the table I'm using to test
CREATE TABLE [dbo].[Authors](
[Client_Id] [nvarchar](50) NOT NULL,
[Project_Id] [nvarchar](50) NOT NULL,
[Person_Id] [int] NOT NULL,
[Author_Number] [int] NOT NULL,
[Family_Name] [nvarchar](50) NULL,
[First_Name] [nvarchar](50) NULL,
)
INSERT INTO Authors (Client_Id, Project_Id, Person_Id, Author_Number, Family_Name, First_Name)
VALUES ('TEST','TEST',12345,1,'Giust','Fede')
INSERT INTO Authors (Client_Id, Project_Id, Person_Id, Author_Number, Family_Name, First_Name)
VALUES ('TEST','TEST',12345,2,'Giust','Fede')
INSERT INTO Authors (Client_Id, Project_Id, Person_Id, Author_Number, Family_Name, First_Name)
VALUES ('TEST','TEST',12346,1,'Giust','Fede')
INSERT INTO Authors (Client_Id, Project_Id, Person_Id, Author_Number, Family_Name, First_Name)
VALUES ('TEST','TEST',12346,2,'Giust','Fede')
INSERT INTO Authors (Client_Id, Project_Id, Person_Id, Author_Number, Family_Name, First_Name)
VALUES ('TEST','TEST',12346,3,'Giust','Fede')
So far I get the results like this
CLIENT_ID PROJECT_ID PERSON_ID AUTHOR_NUMBER FAMILY_NAME FIRST_NAME
TEST TEST 12345 1 Giust Fede
TEST TEST 12345 2 Ma Ke
TEST TEST 12346 1 Jones Peter
TEST TEST 12346 2 Davies Bob
TEST TEST 12346 3 Richards Craig
I need the results to come out like this, and to be dynamic because sometime I can have 2 authors, or 10 authors.
CLIENT_ID PROJECT_ID PERSON_ID FAMILY_NAME_1 FIRST_NAME_1 FAMILY_NAME_2 FIRST_NAME_2 FAMILY_NAME_3 FIRST_NAME_3
TEST TEST 12345 Giust Fede Ma Ke
TEST TEST 12346 Jones Peter Davies Bob Richards Craig
I've been trying to use this code, but keep getting errors
SQL Fiddle

Answer 1

Here are a few suggestions to solve your issue.
First, your current code is unpivoting all of the columns in the table, you only need to UNPIVOT the Family_Name and First_Name columns. As a result I would not use a variable to get this list of columns, just hard-code the two columns you need to unpivot.
Then to get the list of columns to PIVOT, alter the code to use both the Author_number and then a string with the column names Family_Name and First_Name:
select #colsPivot = STUFF((SELECT ',' + QUOTENAME(c.col + '_'+cast(Author_Number as varchar(10)))
from Authors
cross apply
(
select 'Family_Name' col, 1 so union all
select 'First_Name', 2
) c
group by col, author_number, so
order by author_number, so
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
This gives a list of cols:
| COLUMN_0 |
------------------------------------------------------------------------------------------------
| [Family_Name_1],[First_Name_1],[Family_Name_2],[First_Name_2],[Family_Name_3],[First_Name_3] |
Making these changes to your code the final query will be
DECLARE #colsPivot AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #colsPivot = STUFF((SELECT ',' + QUOTENAME(c.col + '_'+cast(Author_Number as varchar(10)))
from Authors
cross apply
(
select 'Family_Name' col, 1 so union all
select 'First_Name', 2
) c
group by col, author_number, so
order by author_number, so
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query
= 'select Client_id, Project_id, Person_Id, '+#colsPivot+'
from
(
select Client_id, Project_id, Person_Id,
col+''_''+cast(Author_Number as varchar(10)) col, val
from
(
select Client_id, Project_id,
Person_Id,
Author_Number,
Family_Name,
First_Name
from Authors
) s
unpivot
(
val
for col in (Family_Name, First_Name)
) u
) x1
pivot
(
max(val)
for col in ('+ #colspivot +')
) p'
exec(#query)
See SQL Fiddle with Demo. This gives a result:
| CLIENT_ID | PROJECT_ID | PERSON_ID | FAMILY_NAME_1 | FIRST_NAME_1 | FAMILY_NAME_2 | FIRST_NAME_2 | FAMILY_NAME_3 | FIRST_NAME_3 |
-----------------------------------------------------------------------------------------------------------------------------------
| TEST | TEST | 12345 | Giust | Fede | Ma | Ke | (null) | (null) |
| TEST | TEST | 12346 | Jones | Peter | Davies | Bob | Richards | Craig |