Question

I have a Monthly Status database view I need to build a report based on. The data in the view looks something like this:

Category | Revenue  |  Yearh  |  Month Bikes      10 000      2008        1 Bikes      12 000      2008        2 Bikes      12 000      2008        3 Bikes      15 000      2008        1 Bikes      11 000      2007        2 Bikes      11 500      2007        3 Bikes      15 400      2007        4 

… And so forth

The view has a product category, a revenue, a year and a month. I want to create a report comparing 2007 and 2008, showing 0 for the months with no sales. So the report should look something like this:

Category  |  Month  |  Rev. This Year  |  Rev. Last Year Bikes          1          10 000               0 Bikes          2          12 000               11 000 Bikes          3          12 000               11 500 Bikes          4          0                    15 400 

The key thing to notice is how month 1 only has sales in 2008, and therefore is 0 for 2007. Also, month 4 only has no sales in 2008, hence the 0, while it has sales in 2007 and still show up.

Also, the report is actually for financial year – so I would love to have empty columns with 0 in both if there was no sales in say month 5 for either 2007 or 2008.

The query I got looks something like this:

SELECT      SP1.Program,     SP1.Year,     SP1.Month,     SP1.TotalRevenue,     IsNull(SP2.TotalRevenue, 0) AS LastYearTotalRevenue  FROM PVMonthlyStatusReport AS SP1       LEFT OUTER JOIN PVMonthlyStatusReport AS SP2 ON                  SP1.Program = SP2.Program AND                  SP2.Year = SP1.Year - 1 AND                  SP1.Month = SP2.Month WHERE      SP1.Program = 'Bikes' AND     SP1.Category = @Category AND      (SP1.Year >= @FinancialYear AND SP1.Year <= @FinancialYear + 1) AND     ((SP1.Year = @FinancialYear AND SP1.Month > 6) OR       (SP1.Year = @FinancialYear + 1 AND SP1.Month <= 6))  ORDER BY SP1.Year, SP1.Month 

The problem with this query is that it would not return the fourth row in my example data above, since we didn’t have any sales in 2008, but we actually did in 2007.

This is probably a common query/problem, but my SQL is rusty after doing front-end development for so long. Any help is greatly appreciated!

Oh, btw, I’m using SQL 2005 for this query so if there are any helpful new features that might help me let me know.

Answer 1

The Case Statement is my best sql friend. You also need a table for time to generate your 0 rev in both months.

Assumptions are based on the availability of following tables:

sales: Category | Revenue | Yearh | Month

and

tm: Year | Month (populated with all dates required for reporting)

Example 1 without empty rows:

select     Category     ,month     ,SUM(CASE WHEN YEAR = 2008 THEN Revenue ELSE 0 END) this_year     ,SUM(CASE WHEN YEAR = 2007 THEN Revenue ELSE 0 END) last_year  from     sales  where     year in (2008,2007)  group by     Category     ,month 

RETURNS:

Category  |  Month  |  Rev. This Year  |  Rev. Last Year Bikes          1          10 000               0 Bikes          2          12 000               11 000 Bikes          3          12 000               11 500 Bikes          4          0                    15 400 

Example 2 with empty rows: I am going to use a sub query (but others may not) and will return an empty row for every product and year month combo.

select     fill.Category     ,fill.month     ,SUM(CASE WHEN YEAR = 2008 THEN Revenue ELSE 0 END) this_year     ,SUM(CASE WHEN YEAR = 2007 THEN Revenue ELSE 0 END) last_year  from     sales     Right join (select distinct  --try out left, right and cross joins to test results.                    product                    ,year                    ,month                from                   sales --this ideally would be from a products table                   cross join tm                where                     year in (2008,2007)) fill   where     fill.year in (2008,2007)  group by     fill.Category     ,fill.month 

RETURNS:

Category  |  Month  |  Rev. This Year  |  Rev. Last Year Bikes          1          10 000               0 Bikes          2          12 000               11 000 Bikes          3          12 000               11 500 Bikes          4          0                    15 400 Bikes          5          0                    0 Bikes          6          0                    0 Bikes          7          0                    0 Bikes          8          0                    0 

Note that most reporting tools will do this crosstab or matrix functionality, and now that i think of it SQL Server 2005 has pivot syntax that will do this as well.

Here are some additional resources. CASE https://web.archive.org/web/20210728081626/https://www.4guysfromrolla.com/webtech/102704-1.shtml SQL SERVER 2005 PIVOT http://msdn.microsoft.com/en-us/library/ms177410.aspx