How can I make “month” columns in Sql?

Question

I\'ve got a set of data that looks something like this (VERY simplified):

productId    Qty   dateOrdered
---------    ---   -----------
       1             


        

Answer 1

This qualifies as a presentation concern.
Presentation and SQL don't always mix well.

Isolating your presentation logic in the application layer will:

1. save you maintenance time—change your application code, but keep your SQL intact;
2. enable you to more quickly adapt to ephemeral client requirements;
3. give you more satisfaction than fiddling with a cross-tab or pivot-table that maddeningly does almost exactly what you want.

Below is an example of how you might do this in Python (you can use the excellent pyodbc module to connect to SQL Server):

from collections import defaultdict
from datetime import date

dd = defaultdict(int)

# input 
rows = [(1,2,date(2008,10,10)), (1,1,date(2008,11,10)), 
        (1,2,date(2009,10,10)), (2,3,date(2009,10,12)), 
        (1,1,date(2009,10,15)), (2,2,date(2009,11,15))]

for row in rows:
    # row[0] == productId
    # row[1] == Qty
    # row[2] == dateOrdered
    # pyodbc enables referring to column names by name
    dd[(row[2].year, row[2].month, row[0])] += row[1]

presentation_rows = sorted(set((i[0], i[2]) for i in dd.keys()))

for i in presentation_rows:
  print i[1], i[0], 
  for j in range(0,13):
    try:
      print dd[i[0], j, i[1]], 
    except IndexError:
      print 0,
  print

# output
# 1 2008 0 0 0 0 0 0 0 0 0 0 2 1 0
# 1 2009 0 0 0 0 0 0 0 0 0 0 3 0 0
# 2 2009 0 0 0 0 0 0 0 0 0 0 3 2 0