PIVOT entire column set by group - sql

Question

For a table like:
COL1 COL2 COL3 COL4
item1 7/29/13 cat blue
item3 7/29/13 fish purple
item1 7/30/13 rat green
item2 7/30/13 bat grey
item3 7/30/13 bird orange
How would you PIVOT to get rows by COL2, all other columns repeated across as blocks by COL1 values?
COL2 COL1 COL3 COL4 COL1 COL3 COL4 COL1 COL3 COL4
7/29/13 item1 cat blue item2 NULL NULL item3 fish purple
7/30/13 item1 rat green item2 bat grey item3 bird orange

Answer 1

In order to get this result you will need to do a few things:
get a distinct list of values from col1 and col2
unpivot the data in your columns col1, col3 and col4
pivot the result from the unpivot
To get the distinct list of dates and items (col1 and col2) along with the values from your existing table you will need to use something similar to the following:
select t.col1, t.col2,
t2.col3, t2.col4,
row_number() over(partition by t.col2
order by t.col1) seq
from
(
select distinct t.col1, c.col2
from yourtable t
cross join
(
select distinct col2
from yourtable
) c
) t
left join yourtable t2
on t.col1 = t2.col1
and t.col2 = t2.col2;
See SQL Fiddle with Demo. Once you have this list, then you will need to unpivot the data. There are several ways you can do this, using the UNPIVOT function or using CROSS APPLY:
select d.col2,
col = col+'_'+cast(seq as varchar(10)),
value
from
(
select t.col1, t.col2,
t2.col3, t2.col4,
row_number() over(partition by t.col2
order by t.col1) seq
from
(
select distinct t.col1, c.col2
from yourtable t
cross join
(
select distinct col2
from yourtable
) c
) t
left join yourtable t2
on t.col1 = t2.col1
and t.col2 = t2.col2
) d
cross apply
(
select 'col1', col1 union all
select 'col3', col3 union all
select 'col4', col4
) c (col, value);
See SQL Fiddle with Demo. this will give you data that looks like:
| COL2 | COL | VALUE |
-------------------------------------------------
| July, 29 2013 00:00:00+0000 | col1_1 | item1 |
| July, 29 2013 00:00:00+0000 | col3_1 | cat |
| July, 29 2013 00:00:00+0000 | col4_1 | blue |
| July, 29 2013 00:00:00+0000 | col1_2 | item2 |
| July, 29 2013 00:00:00+0000 | col3_2 | (null) |
| July, 29 2013 00:00:00+0000 | col4_2 | (null) |
Finally, you will apply the PIVOT function to the items in the col columns:
select col2,
col1_1, col3_1, col4_1,
col1_2, col3_2, col4_2,
col1_3, col3_3, col4_3
from
(
select d.col2,
col = col+'_'+cast(seq as varchar(10)),
value
from
(
select t.col1, t.col2,
t2.col3, t2.col4,
row_number() over(partition by t.col2
order by t.col1) seq
from
(
select distinct t.col1, c.col2
from yourtable t
cross join
(
select distinct col2
from yourtable
) c
) t
left join yourtable t2
on t.col1 = t2.col1
and t.col2 = t2.col2
) d
cross apply
(
select 'col1', col1 union all
select 'col3', col3 union all
select 'col4', col4
) c (col, value)
) src
pivot
(
max(value)
for col in (col1_1, col3_1, col4_1,
col1_2, col3_2, col4_2,
col1_3, col3_3, col4_3)
)piv;
See SQL Fiddle with Demo. If you have an unknown number of values, then you can use dynamic SQL to get the result:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(col+'_'+cast(seq as varchar(10)))
from
(
select row_number() over(partition by col2
order by col1) seq
from yourtable
) t
cross apply
(
select 'col1', 1 union all
select 'col3', 2 union all
select 'col4', 3
) c (col, so)
group by col, seq, so
order by seq, so
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT col2, ' + #cols + '
from
(
select d.col2,
col = col+''_''+cast(seq as varchar(10)),
value
from
(
select t.col1, t.col2,
t2.col3, t2.col4,
row_number() over(partition by t.col2
order by t.col1) seq
from
(
select distinct t.col1, c.col2
from yourtable t
cross join
(
select distinct col2
from yourtable
) c
) t
left join yourtable t2
on t.col1 = t2.col1
and t.col2 = t2.col2
) d
cross apply
(
select ''col1'', col1 union all
select ''col3'', col3 union all
select ''col4'', col4
) c (col, value)
) x
pivot
(
max(value)
for col in (' + #cols + ')
) p '
execute sp_executesql #query;
See SQL Fiddle with Demo. All versions will give a result:
| COL2 | COL1_1 | COL3_1 | COL4_1 | COL1_2 | COL3_2 | COL4_2 | COL1_3 | COL3_3 | COL4_3 |
----------------------------------------------------------------------------------------------------------------
| July, 29 2013 00:00:00+0000 | item1 | cat | blue | item2 | (null) | (null) | item3 | fish | purple |
| July, 30 2013 00:00:00+0000 | item1 | rat | green | item2 | bat | grey | item3 | bird | orange |

Answer 2

The dynamic UNPIVOT+PIVOT method is always cool, when doing this sort of thing for a known and limited set of values subsequent JOIN's work nicely too (being lazy on the SELECT list):
WITH cte AS (SELECT *,ROW_NUMBER() OVER (PARTITION BY COL2 ORDER BY COL1)'RowRank'
FROM #Table1)
SELECT *
FROM cte a
LEFT JOIN cte b
ON a.COL2 = b.COL2
AND a.RowRank = b.RowRank - 1
LEFT JOIN cte c
ON b.COL2 = c.COL2
AND b.RowRank = c.RowRank - 1
WHERE a.RowRank = 1
Or if the order of the fields is to be maintained:
WITH cte AS (SELECT a.*,b.RowRank
FROM #Table1 a
JOIN (SELECT Col1,ROW_NUMBER() OVER (ORDER BY Col1)'RowRank'
FROM #Table1
GROUP BY COL1) b
ON a.Col1 = b.Col1)
SELECT *
FROM cte a
LEFT JOIN cte b
ON a.COL2 = b.COL2
AND a.RowRank = b.RowRank - 1
LEFT JOIN cte c
ON a.COL2 = c.COL2
AND a.RowRank = c.RowRank - 2
WHERE a.RowRank = 1
But this falls apart without an 'anchor' value, ie if no record had item1 for a given date it wouldn't be included.