Dynamic pivot table or what? - sql

Question

I have a table that consists of pageno int, groupid varchar(10). Each row in the table is distinct. There can be multiple groupid and pageno combinations. The amount of pagenos is unknown and the amount of groupids is unknown. The data might look like this:
pageno groupid
101105 mpadilla
101105 gentry
100100 mpadilla
100100 gentry
I would like to have a result set returned that shows the pagenos as columns and the groupids as rows and an x where they intersect (meaning it exists for that pageno/groupid combo).
Would I use sql pivot for this? If so, give me an example please. If not, please provide your example and explanation. I'm a little confused.

Answer 1

Your requirements are not entirely clear but if I am understanding your question you can use the PIVOT function to get the result.
The basic syntax for this query of query would be the following if you had a limited number of pagenos:
select groupid, [101105], [100100]
from
(
select pageno, groupid,
flag = 'X'
from yourtable
) d
pivot
(
max(flag)
for pageno in ([101105], [100100])
) piv;
See SQL Fiddle with Demo.
Then if you have an unknown number of values, you will need to use dynamic SQL:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(pageno)
from yourtable
group by pageno
order by pageno
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT groupid, ' + #cols + '
from
(
select pageno, groupid,
flag = ''X''
from yourtable
) x
pivot
(
max(flag)
for pageno in (' + #cols + ')
) p '
execute sp_executesql #query;
See SQL Fiddle with Demo. Both versions will give a result:
| GROUPID | 100100 | 101105 |
| gentry | X | X |
| mpadilla | X | X |
| test | X | (null) |
Edit, if you have nulls that you want to replace, then I would create a second list of column names this one will be used for the final select list and it will include coalesce to replace the null. The code will be:
DECLARE #cols AS NVARCHAR(MAX),
#colsNull AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(pageno)
from yourtable
group by pageno
order by pageno
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
select #colsNull = STUFF((SELECT ', coalesce(' + QUOTENAME(pageno) +', '''') as '+QUOTENAME(pageno)
from yourtable
group by pageno
order by pageno
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT groupid, ' + #colsNull + '
from
(
select pageno, groupid,
flag = ''X''
from yourtable
) x
pivot
(
max(flag)
for pageno in (' + #cols + ')
) p '
execute sp_executesql #query;
See SQL Fiddle with Demo. The result will be:
| GROUPID | 100100 | 101105 |
| gentry | X | X |
| mpadilla | X | X |
| test | X | |

Answer 2

I answered my own question. What I did was add an additional column called customized to my original table. This column only contains an x for each customized page. Kind of redundant I know but it seems that the pivot table needs 3 columns. So here is my dynamic code that I came up with and works:
DECLARE #query VARCHAR(4000), #groupids VARCHAR(8000)
SELECT #groupids = STUFF(( SELECT DISTINCT
'],[' + LTRIM(groupid)
FROM DistinctPages
ORDER BY '],[' + LTRIM(groupid)
FOR XML PATH('')
), 1,2, '') + ']'
SET #query =
'SELECT * FROM (SELECT pageno, groupid, customized FROM DistinctPages)t
PIVOT (MAX(customized) FOR groupid
IN ('+#groupids+')) AS CustomizedPagesPerGroups'
EXECUTE (#query)