Re: how to generate SQL SELECT pivot table string

[Michael Spencer]

McBooCzech wrote:
Hallo all,
I am trying to generate SQL SELECT command which will return pivot
table. The number of column in the pivot table depends on the data
stored in the database. It means I do not know in advance how many
columns the pivot table will have.
For example I will test the database as following:
SELECT DISTINCT T1.YEAR FROM T1
The SELECT command will return:
2002
2003
2004
2005
So I would like to construct following select:
select T1.WEEK,
SUM (case T1.YEAR when '2002' then T1.PRICE else 0 END) Y_02,
SUM (case T1.YEAR when '2003' then T1.PRICE else 0 END) Y_03,
SUM (case T1.YEAR when '2004' then T1.PRICE else 0 END) Y_04,
SUM (case T1.YEAR when '2005' then T1.PRICE else 0 END) Y_05
from T1
group by T1.week
which will return pivot table with 5 columns:
WEEK, Y_02, Y_03, Y_04, Y_05,
but if the command "SELECT DISTINCT T1.YEAR FROM T1" returns:
2003
2004
I have to construct only following string:
select T1.WEEK,
SUM (case T1.YEAR when '2003' then T1.PRICE else 0 END) Y_03,
SUM (case T1.YEAR when '2004' then T1.PRICE else 0 END) Y_04,
from T1
group by T1.week
which will return pivot table with 3 columns:
WEEK, Y_03, Y_04
Can anyone help and give me a hand or just direct me, how to write a
code which will generate SELECT string depending on the data stored in
the database as I described?
Thanks
Petr McBooCzech
>>> step1result = """2000
... 2001
... 2002
... 2003""".splitlines()
>>> step1result
['2000', '2001', '2002', '2003']
>>> step2query = "Prefix " + ",".join(["Case %s" % year for year in 
step1result]) + " Postfix"
>>> step2query
'Prefix Case 2000,Case 2001,Case 2002,Case 2003 Postfix'

HTH
Michael
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