Using PIVOT on a calendar in SQL Server 2005 - sql-server-2005

Question

I have the following problem: I need to implement a calendar using SQL Server 2005. Here's an example of what my stored procedure gives me so far:
TIME | DATE | CALENDAR_ID | SUBJECT | NOTES | STATUS_ID
===================================================================
09:00 | 19/08/2013 | 1 | SUBJECT 1 | NOTES 1 | 1
10:00 | 19/08/2013 | 2 | SUBJECT 2 | NOTES 2 | 2
11:00 | 19/08/2013 | 3 | SUBJECT 3 | NOTES 3 | 3
12:00 | 19/08/2013 | 4 | SUBJECT 4 | NOTES 4 | 1
09:00 | 20/08/2013 | 5 | SUBJECT 5 | NOTES 5 | 4
10:00 | 20/08/2013 | 6 | SUBJECT 6 | NOTES 6 | 3
11:00 | 20/08/2013 | 7 | SUBJECT 7 | NOTES 7 | 1
12:00 | 20/08/2013 | 8 | SUBJECT 8 | NOTES 8 | 1
But I'd like to display it like this:
TIME | 19/08/2013 | 20/08/2013
===============================
09:00 | SUBJECT 1 | SUBJECT 5
10:00 | SUBJECT 2 | SUBJECT 6
11:00 | SUBJECT 3 | SUBJECT 7
12:00 | SUBJECT 4 | SUBJECT 8
I know about the PIVOT function in SQL Server which seems to be useful for these cases, and I searched for examples and explanations, but I still don't understand completely. Besides, so far I've seen only examples like getting the total sum of sales per month; I'm not sure my calendar could use the same logic (or even if I can do what I intend to do using PIVOT). Anyway, could someone point me in the right direction about my problem? Thanks in advance.

Answer 1

Yes you can use the PIVOT function to convert the rows of data into columns. You will just use the aggregate function max or min to select the subject for each date. If you have a limited number of dates that you want to convert into columns then you can hard-code the query:
select [time], [19/08/2013], [20/08/2013]
from
(
select [time], [date], subject
from yourtable
) d
pivot
(
max(subject)
for [date] in ([19/08/2013], [20/08/2013])
) piv;
See SQL Fiddle with Demo
But if you have an unknown number of values, then you can use dynamic SQL in a stored procedure to get the result:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT distinct ',' + QUOTENAME(DATE)
from yourtable
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT [time], ' + #cols + '
from
(
select [time], [date], subject
from yourtable
) x
pivot
(
max(subject)
for [date] in (' + #cols + ')
) p '
execute sp_executesql #query;
See SQL Fiddle with Demo. Both will give a result:
| TIME | 19/08/2013 | 20/08/2013 |
-----------------------------------
| 09:00 | SUBJECT 1 | SUBJECT 5 |
| 10:00 | SUBJECT 2 | SUBJECT 6 |
| 11:00 | SUBJECT 3 | SUBJECT 7 |
| 12:00 | SUBJECT 4 | SUBJECT 8 |