Pivoting rows into columns in SQL Server - sql

Question

I have a set of data that looks like this:
Before
FirstName LastName Field1 Field2 Field3 ... Field27
--------- -------- ------ ------ ------ -------
Mark Smith A B C D
John Baptist X T Y G
Tom Dumm R B B U
However, I'd like the data to look like this:
After
FirstName LastName Field Value
--------- -------- ----- -----
Mark Smith 1 A
Mark Smith 2 B
Mark Smith 3 C
Mark Smith 4 D
John Baptist 1 X
John Baptist 2 T
John Baptist 3 Y
John Baptist 4 G
Tom Dumm 1 R
Tom Dumm 2 B
Tom Dumm 3 B
Tom Dumm 4 U
I have looked at the PIVOT function. It may work. I am not too sure. I couldn't make sense of how to use it. But, I am not sure that the pivot could place a '4' in the 'Field' column. From my understanding, the PIVOT function would simply transpose the values of Field1...Field27 into the 'Value' column.
I have also considered iterating over the table with a Cursor and then looping over the field columns, and then INSERTing into another table the 'Field's and 'Value's. However, I know this will impact performance since it's a serial-based operation.
Any help would be greatly appreciated! As you can tell, I'm quite new to T-SQL (or SQL in general) and SQL Server.

Answer 1

You can perform with an UNPIVOT. There are two ways to do this:
1) In a Static Unpivot you would hard-code your Field columns in your query.
select firstname
, lastname
, replace(field, 'field', '') as field
, value
from test
unpivot
(
value
for field in (field1, field2, field3, field27)
) u
See a SQL Fiddle for a working demo.
2) Or you could use a Dynamic Unpivot which will get the list of items to PIVOT when you run the SQL. The Dynamic is great if you have a large amount of fields that you will be unpivoting.
create table mytest
(
firstname varchar(5),
lastname varchar(10),
field1 varchar(1),
field2 varchar(1),
field3 varchar(1),
field27 varchar(1)
)
insert into mytest values('Mark', 'Smith', 'A', 'B', 'C', 'D')
insert into mytest values('John', 'Baptist', 'X', 'T', 'Y', 'G')
insert into mytest values('Tom', 'Dumm', 'R', 'B', 'B', 'U')
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX);
select #cols = stuff((select ','+quotename(C.name)
from sys.columns as C
where C.object_id = object_id('mytest') and
C.name like 'Field%'
for xml path('')), 1, 1, '')
set #query = 'SELECT firstname, lastname, replace(field, ''field'', '''') as field, value
from mytest
unpivot
(
value
for field in (' + #cols + ')
) p '
execute(#query)
drop table mytest
Both will produce the same results.

Answer 2

If you want to do it query than quick and dirty way will be to create Union
Select FirstName,LastName,1,Field1
from table
UNION ALL
Select FirstName,LastName,2,Field2
from table
.
.
And similar for all field cols

Answer 3

Rather than using pivot, use unpivot like this:
select firstname, lastname, substring(field,6,2) as field, value
from <yourtablename>
unpivot(value for field in (field1,field2,field3,field4,field5,field6,field7,field8,field9,field10,field11,field12,field13,field14,field15,field16,field17,field18,field19,field20,field21,field22,field23,field24,field25,field26,field27,field1,field2,field3,field4,field5,field6,field7,field8,field9,field10,field11,field12,field13,field14,field15,field16,field17,field18,field19,field20,field21,field22,field23,field24,field25,field26,field27)) as unpvt;