Let’s start with a fictional scenario.
In this case we have lots of vendors who report in their daily income to us, for this we have a simple table that looks like this.
create table DailyIncome(VendorId nvarchar(10), IncomeDay nvarchar(10), IncomeAmount int)
--drop table DailyIncome
Nothing odd here, just the Vendor id, the day of the week they are referring to and what the income on that day was.
So let’s fill it with some data.
insert into DailyIncome values ('SPIKE', 'FRI', 100)
insert into DailyIncome values ('SPIKE', 'MON', 300)
insert into DailyIncome values ('FREDS', 'SUN', 400)
insert into DailyIncome values ('SPIKE', 'WED', 500)
insert into DailyIncome values ('SPIKE', 'TUE', 200)
insert into DailyIncome values ('JOHNS', 'WED', 900)
insert into DailyIncome values ('SPIKE', 'FRI', 100)
insert into DailyIncome values ('JOHNS', 'MON', 300)
insert into DailyIncome values ('SPIKE', 'SUN', 400)
insert into DailyIncome values ('JOHNS', 'FRI', 300)
insert into DailyIncome values ('FREDS', 'TUE', 500)
insert into DailyIncome values ('FREDS', 'TUE', 200)
insert into DailyIncome values ('SPIKE', 'MON', 900)
insert into DailyIncome values ('FREDS', 'FRI', 900)
insert into DailyIncome values ('FREDS', 'MON', 500)
insert into DailyIncome values ('JOHNS', 'SUN', 600)
insert into DailyIncome values ('SPIKE', 'FRI', 300)
insert into DailyIncome values ('SPIKE', 'WED', 500)
insert into DailyIncome values ('SPIKE', 'FRI', 300)
insert into DailyIncome values ('JOHNS', 'THU', 800)
insert into DailyIncome values ('JOHNS', 'SAT', 800)
insert into DailyIncome values ('SPIKE', 'TUE', 100)
insert into DailyIncome values ('SPIKE', 'THU', 300)
insert into DailyIncome values ('FREDS', 'WED', 500)
insert into DailyIncome values ('SPIKE', 'SAT', 100)
insert into DailyIncome values ('FREDS', 'SAT', 500)
insert into DailyIncome values ('FREDS', 'THU', 800)
insert into DailyIncome values ('JOHNS', 'TUE', 600)
Now, if we select out the flat data that we have, we will get the following:
VendorId IncomeDay IncomeAmount
---------- ---------- ------------
SPIKE FRI 100
SPIKE MON 300
FREDS SUN 400
SPIKE WED 500
SPIKE TUE 200
JOHNS WED 900
SPIKE FRI 100
JOHNS MON 300
SPIKE SUN 400
...
SPIKE WED 500
FREDS THU 800
JOHNS TUE 600
A lot of data that it is hard to make something useful of, for example, say that we would like to know what the average income is for each vendor id?
Or what the maximum income is for each day for a particular vendor? Enter the pivot table.
To find the average for each vendor, run this query:
select * from DailyIncome
pivot (avg (IncomeAmount) for IncomeDay in ([MON],[TUE],[WED],[THU],[FRI],[SAT],[SUN])) as AvgIncomePerDay
Outcome:
VendorId MON TUE WED THU FRI SAT SUN
---------- ----------- ----------- ----------- ----------- ----------- ----------- -----------
FREDS 500 350 500 800 900 500 400
JOHNS 300 600 900 800 300 800 600
SPIKE 600 150 500 300 200 100 400
The find the max income for each day for vendor SPIKE, run this query:
select * from DailyIncome
pivot (max (IncomeAmount) for IncomeDay in ([MON],[TUE],[WED],[THU],[FRI],[SAT],[SUN])) as MaxIncomePerDay
where VendorId in ('SPIKE')
Outcome:
VendorId MON TUE WED THU FRI SAT SUN
---------- ----------- ----------- ----------- ----------- ----------- ----------- -----------
SPIKE 900 200 500 300 300 100 400
The short story on how it works using the last query.
select * from DailyIncome -- Colums to pivot
pivot (
max (IncomeAmount) -- Pivot on this column
for IncomeDay in ([MON],[TUE],[WED],[THU],[FRI],[SAT],[SUN])) -- Make colum where IncomeDay is in one of these.
as MaxIncomePerDay -- Pivot table alias
where VendorId in ('SPIKE') -- Select only for this vendor
The above post is taken from Pivot tables in SQL Server.
The above post is taken from Pivot tables in SQL Server.
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