Convert Rows to columns using 'Pivot' in SQL Server

Question

I have read the stuff on MS pivot tables and I am still having problems getting this correct.

I have a temp table that is being created, we will say that column 1 is a Store number, and column 2 is a week number and lastly column 3 is a total of some type. Also the Week numbers are dynamic, the store numbers are static.

Store      Week     xCount
-------    ----     ------
102        1        96
101        1        138
105        1        37
109        1        59
101        2        282
102        2        212
105        2        78
109        2        97
105        3        60
102        3        123
101        3        220
109        3        87

I would like it to come out as a pivot table, like this:

Store        1          2          3        4        5        6....
----- 
101        138        282        220
102         96        212        123
105         37        
109

Store numbers down the side and weeks across the top.

Answer 1

If you are using SQL Server 2005+, then you can use the PIVOT function to transform the data from rows into columns.

It sounds like you will need to use dynamic sql if the weeks are unknown but it is easier to see the correct code using a hard-coded version initially.

First up, here are some quick table definitions and data for use:

CREATE TABLE #yt 
(
  [Store] int, 
  [Week] int, 
  [xCount] int
);

INSERT INTO #yt
(
  [Store], 
  [Week], [xCount]
)
VALUES
    (102, 1, 96),
    (101, 1, 138),
    (105, 1, 37),
    (109, 1, 59),
    (101, 2, 282),
    (102, 2, 212),
    (105, 2, 78),
    (109, 2, 97),
    (105, 3, 60),
    (102, 3, 123),
    (101, 3, 220),
    (109, 3, 87);

If your values are known, then you will hard-code the query:

select *
from 
(
  select store, week, xCount
  from yt
) src
pivot
(
  sum(xcount)
  for week in ([1], [2], [3])
) piv;

See SQL Demo

Then if you need to generate the week number dynamically, your code will be:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT ',' + QUOTENAME(Week) 
                    from yt
                    group by Week
                    order by Week
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT store,' + @cols + ' from 
             (
                select store, week, xCount
                from yt
            ) x
            pivot 
            (
                sum(xCount)
                for week in (' + @cols + ')
            ) p '

execute(@query);

See SQL Demo.

The dynamic version, generates the list of week numbers that should be converted to columns. Both give the same result:

| STORE |   1 |   2 |   3 |
---------------------------
|   101 | 138 | 282 | 220 |
|   102 |  96 | 212 | 123 |
|   105 |  37 |  78 |  60 |
|   109 |  59 |  97 |  87 |