Right using of PIVOT-statement in SQL Server - sql-server

Question

I have an audit table, part of data is looked like:
Id ColumnName Value RowId
---------------------------------
1 EditCheckId 100 1
2 FieldData_Id 10 1
3 EditType 1 1
4 Outcome True 1
5 EditCheckId 200 2
6 FieldData_Id 20 2
7 EditType 2 2
8 Outcome False 2
9 EditCheckId 300 3
10 FieldData_Id 30 3
11 EditType 3 3
12 Outcome True 3
and I want to construct such table groupping data by RowId
EditCheck_Id FieldData_Id EditType Outcome
---------------------------------------------------
100 10 1 True
200 20 2 False
300 30 3 True
I've tried the query:
select [EditCHeck_Id], [FieldData_Id], [EditType], [Outcome]
from
(
select [ColumnName], [Value]
from Audit a
) as [SourceTable]
pivot
(
max([Value])
for [ColumnName] in ([EditCHeck_Id], [FieldData_Id], [EditType], [Outcome])
) as [PivotTable];
http://sqlfiddle.com/#!6/7af71/3
using PIVOT statement but there is only one row in answer. Where is my problem?

Answer 1

You'll need some value to GROUP BY to make each of the rows distinct. Typically, you would use a windowing function like row_number() to generate a unique sequenced number over your current columnname. You can alter your query to the following:
select
[EditCheckId],
[FieldData_Id],
[EditType],
[Outcome]
from
(
select [ColumnName], [Value],
rn = row_number() over(partition by ColumnName order by id)
from Audit a
) as [SourceTable]
pivot
(
max([Value])
for [ColumnName] in ([EditCheckId], [FieldData_Id], [EditType], [Outcome])
) as [PivotTable];
See SQL Fiddle with Demo.
You could also use an aggregate function with a CASE expression to get the final result:
select
max(case when ColumnName = 'EditCheckId' then value end) [EditCheckId],
max(case when ColumnName = 'FieldData_Id' then value end) [FieldData_Id],
max(case when ColumnName = 'EditType' then value end) [EditType],
max(case when ColumnName = 'Outcome' then value end) [Outcome]
from
(
select [ColumnName], [Value],
rn = row_number() over(partition by ColumnName order by id)
from Audit a
) d
group by rn;
See SQL Fiddle with Demo Both give the result:
| EDITCHECKID | FIELDDATA_ID | EDITTYPE | OUTCOME |
|-------------|--------------|----------|---------|
| 100 | 10 | 1 | True |
| 200 | 20 | 2 | False |
| 300 | 30 | 3 | True |

Answer 2

You need something to distinguish the output rows, like for example your RowId
pivot does the grouping for you like so:
select [RowID], [EditCheckId], [FieldData_Id], [EditType], [Outcome]
from
(
select [ColumnName], [Value], [RowId]
from Audit a
) as [SourceTable]
pivot
(
max([Value])
for [ColumnName] in ([EditCheckId], [FieldData_Id], [EditType], [Outcome])
) as [PivotTable];
edited Fiddle demo