SQL Query for report - sql

Question

I am working on a aggregate report and I have got so far with the data but I am unsure how to proceed from here. I get by with SQL but my skills are limited
I have the follow in a temp table
ID Count Action
2 23 Installed
2 12 Uninstalled
2 36 Unchanged
3 12 Installed
3 25 Unchanged
4 35 Installed
4 25 Unchanged
I want to convert this into this format
ID Installed Uninstalled Unchanged
2 23 12 36
3 12 0 36
4 35 0 25
I have no idea where to go or even how to start to achieve this and cannot find anything to point me in the right direction (Im sure its there somewhere)
Any help would be appriciated

Answer 1

Try this:
SELECT
ID,
MAX(CASE WHEN "Action" = 'Installed' THEN Count END) AS 'Installed',
MAX(CASE WHEN "Action" = 'Uninstalled ' THEN Count END) AS 'Uninstalled',
MAX(CASE WHEN "Action" = 'Unchanged' THEN Count END) AS 'Unchanged'
FROM Table
GROUP BY ID;
Or using the SQL Server PIVOT table operator like so:
SELECT *
FROM
(
SELECT * FROM table
)t
PIVOT
(
MAX("Count") FOR "Action" IN([Installed], [Uninstalled], [Unchanged])
) p
SQL Fiddle Demo for both
However, for unknown number of Actions, you will have to select them dynamically like so:
DECLARE #cols AS NVARCHAR(MAX);
DECLARE #query AS NVARCHAR(MAX);
select #cols = STUFF((SELECT distinct ',' + QUOTENAME(Action)
from Table1
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'');
SET #query = 'SELECT ID, ' + #cols + ' from
(
SELECT * FROM Table1
) x
PIVOT
(
MAX(count)
FOR action IN (' + #cols + ')
) p ';
EXECUTE(#query);
SQL Fiddle Demo(Dynamic Version)

Answer 2

It's called a pivot
Here's the documentation about it
The syntax is
SELECT <non-pivoted column>,
[first pivoted column] AS <column name>,
[second pivoted column] AS <column name>,
...
[last pivoted column] AS <column name>
FROM
(<SELECT query that produces the data>)
AS <alias for the source query>
PIVOT
(
<aggregation function>(<column being aggregated>)
FOR
[<column that contains the values that will become column headers>]
IN ( [first pivoted column], [second pivoted column],
... [last pivoted column])
) AS <alias for the pivot table>
<optional ORDER BY clause>;

Answer 3

Pivots are good, but very slow at times. Try it without one.
SELECT ID
, SUM(CASE WHEN [Action] = 'Installed' THEN [Count] ELSE 0 END) AS Installed
, SUM(CASE WHEN [Action] = 'Uninstalled' THEN [Count] ELSE 0 END) AS Uninstalled
, SUM(CASE WHEN [Action] = 'Unchanged' THEN [Count] ELSE 0 END) AS Unchanged
FROM <table>
GROUP BY ID