使用SQL Server PIVOTing数据

Question

Okay, I have hit the bull's eye when I even didn't know how to fire a gun. I wrote this SQL based on Technet basic article ( http://technet.microsoft.com/en-us/library/ms177410(v=sql.105).aspx )

Select LogTime, Location, LA95Day, LA95Evening, LA95DEn, LA95Night from 
(Select LogTime, Location, LAValue, ValueType  from Project_5_CalculatedData 
     where ValueType in ('LA95Day','LA95Evening','LA95DEn','LA95Night')  )  as c
PIVOT(
Max(LAValue) For ValueType in (LA95Day,LA95Evening,LA95DEn,LA95Night)) as PVt

My Table structure is something like

DataID  Location    LogTime LAValue ValueType
10117   Meter1  2012-09-25 00:00:00.000 71.12   LA95Day
10118   Meter1  2012-09-25 00:00:00.000 55.52   LA95Evening
10119   Meter1  2012-09-25 00:00:00.000 52.69   LA95Night
10120   Meter1  2012-09-25 00:00:00.000 68.62   LA95Den
10121   Meter1  2012-09-26 00:00:00.000 72.21   LA95Day
10122   Meter1  2012-09-26 00:00:00.000 54.10   LA95Evening
10123   Meter1  2012-09-26 00:00:00.000 48.30   LA95Night
10124   Meter1  2012-09-26 00:00:00.000 69.38   LA95Den

EDIT : Data is incomplete here.. we have 4000 rows .. so you can assume MEter2, Meter3, Meter4 location will exists with same or different days as in sample data. ** Edit Ends **

we have upto 4 Meters to record the values, DataID is not important. However I want all Meter data to be aligned, the above query that I wrote does it's work partially, ie it shows data as :

LogTime Location    LA95Day LA95Evening LA95DEn LA95Night
2012-09-25 00:00:00.000 Meter1  71.12   55.52   68.62   52.69
2012-09-26 00:00:00.000 Meter1  72.21   54.10   69.38   48.30
2012-09-27 00:00:00.000 Meter1  68.88   47.77   66.05   46.02
2012-09-28 00:00:00.000 Meter1  73.52   49.23   70.56   43.60
2012-09-29 00:00:00.000 Meter1  54.09   44.87   52.85   41.64
2012-09-30 00:00:00.000 Meter1  51.46   48.61   51.94   41.60
2012-10-01 00:00:00.000 Meter1  73.09   51.78   70.17   46.20

But I want that based on meter used; LAday, evening, Den and night will get repeated up to 4 time; once per meter used in application. ie desire output [columns] needs to be

LogTime M1-LA95Day  M1-LA95Evening  M1-LA95DEn  M1-LA95Night M2-LA95Day M2-LA95Evening  M2-LA95DEn  M2-LA95Night M3-LA95Day M3-LA95Evening  M3-LA95DEn  M3-LA95Night M4-LA95Day M4-LA95Evening  M4-LA95DEn  M4-LA95Night

Oh, I am trying via hit and trial as I never use Pivot before and doesn't know even how my above query works, if you can just explain that query will help me do next step. thanks.

Answer 1

It seems to me that you are trying to list all meters along with their valueTypes as columns. If that is the case, then you should be able to use the following:

Select LogTime, 
    Meter1_LA95Day, Meter1_LA95Evening, Meter1_LA95DEn, Meter1_LA95Night,
    Meter2_LA95Day, Meter2_LA95Evening, Meter2_LA95DEn, Meter2_LA95Night,
    Meter3_LA95Day, Meter3_LA95Evening, Meter3_LA95DEn, Meter3_LA95Night,
    Meter4_LA95Day, Meter4_LA95Evening, Meter4_LA95DEn, Meter4_LA95Night 
from 
(
    Select LogTime, 
        ValueType = Location+'_'+ValueType,
        LAValue       
    from Project_5_CalculatedData 
    where ValueType in ('LA95Day','LA95Evening','LA95DEn','LA95Night')  
)  as c
PIVOT
(
    Max(LAValue) 
    For ValueType in (Meter1_LA95Day, Meter1_LA95Evening, Meter1_LA95DEn, Meter1_LA95Night,
                      Meter2_LA95Day, Meter2_LA95Evening, Meter2_LA95DEn, Meter2_LA95Night,
                      Meter3_LA95Day, Meter3_LA95Evening, Meter3_LA95DEn, Meter3_LA95Night,
                      Meter4_LA95Day, Meter4_LA95Evening, Meter4_LA95DEn, Meter4_LA95Night)
) as PVt;

Note, this assumes the meters are actually named meter1 , meter2 , etc. If your meters aren't called meter1 , etc and they have names that might not be the same, then you might want to use dynamic SQL to get the result:

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

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(Location+'_'+ValueType) 
                    from Project_5_CalculatedData
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT LogTime,' + @cols + ' 
            from 
            (
                Select LogTime, 
                    ValueType = Location+''_''+ValueType,
                    LAValue       
                from Project_5_CalculatedData 
                where ValueType in (''LA95Day'',''LA95Evening'',''LA95DEn'',''LA95Night'')  
            ) x
            pivot 
            (
                max(LAValue)
                for ValueType in (' + @cols + ')
            ) p '

execute sp_executesql @query;

These will give a result:

+-------------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+
|         LogTime         | Meter1_LA95Day | Meter1_LA95Den | Meter1_LA95Evening | Meter1_LA95Night | Meter2_LA95Day | Meter2_LA95Den | Meter2_LA95Evening | Meter2_LA95Night | Meter3_LA95Day | Meter3_LA95Den | Meter3_LA95Evening | Meter3_LA95Night |
+-------------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+
| 2012-09-25 00:00:00.000 | 71.12          | 68.62          | 55.52              | 52.69            | 71.12          | 68.62          | 55.52              | 52.69            | NULL           | NULL           | NULL               | NULL             |
| 2012-09-26 00:00:00.000 | 72.21          | 69.38          | 54.10              | 48.30            | NULL           | NULL           | NULL               | NULL             | 72.21          | 69.38          | 54.10              | 48.30            |
+-------------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+----------------+----------------+--------------------+------------------+